Resin composition and cured product thereof

ABSTRACT

The present invention provides a resin composition which can be cured in a short time without a heat load on an adherend and with which a cured product having stable quality can be obtained. The resin composition in accordance with the present invention contains (i) a bisphenol A epoxy resin, (ii) an encapsulated curing agent including a core that contains a curing agent and a shell that covers the core, (iii) a filler, and (iv) a color material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Stage of International ApplicationNo. PCT/JP2014/079460, filed on Nov. 6, 2014, claiming priority based onJapanese Patent Application No. 2014-052106, filed on Mar. 14, 2014, thecontents of all of which are herein incorporated by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to a resin composition and a cured productof the resin composition. Specifically, the present invention relates to(i) a resin composition with which curing can be carried out in a shorttime without placing a heat load on an adherend and from which a curedproduct having stable bonding quality can be obtained and (ii) a curedproduct of the resin composition.

BACKGROUND ART

Conventionally, as a method (hereinafter, referred to as “sealingmethod”) for sealing members in an electronic component or the like oras a method (hereinafter, referred to as “bonding method”) for bondingmembers together in an electronic component or the like, the followingmethods and the like are known: that is, (1) a method in which aone-part epoxy resin adhesive agent is applied to a member and theadhesive agent is cured by heating; (2) a method in which a two-partepoxy resin adhesive agent is mixed and applied to a member, and is thencured by being left to stand; (3) a method in which a UV-curableadhesive agent is used; and (4) a method in which an instant adhesiveagent is used.

Moreover, various techniques have been developed for dealing withdifferent problems caused in a conventionally known sealing method orbonding method or in a conventionally known case where a sealing agentor adhesive agent is used.

For example, Patent Literature 1 discloses a technique in which, inorder to prevent diffusion of heat energy generated by a curing reactioninside a curable resin composition in a complex in which the curableresin composition is attached onto metal or the like, a surface of ahighly heat conductive member such as metal is coated with a materialhaving low heat conductivity, a curable resin composition layer isformed thereon and is irradiated with energy, and thus continuous curingwith the heat energy can be carried out. It is also disclosed in PatentLiterature 1 that, in that case, an energy beam such as an ultravioletray (UV), an electron beam (EB), or a laser or heat energy or the likeby conduction can be used.

Moreover, for example, Patent Literature 2 discloses an adhesive agentcomposition which contains a powder component such as a filler and canbe stably applied without containing gas bubbles even in a case where anamount of the adhesive agent composition to be applied is small.Further, Patent Literature 2 discloses that the composition is cured byheat, and a microencapsulated cure-accelerating agent can be used as acomponent of the composition.

CITATION LIST Patent Literature

[Patent Literature 1]

Japanese Patent Application Publication Tokukai No. 2011-194597(Publication date: Oct. 6, 2011)

[Patent Literature 2]

Japanese Patent Application Publication Tokukai No. 2012-224733(Publication date: Nov. 15, 2012)

SUMMARY OF INVENTION Technical Problem

However, the methods (1) through (4) above have the following problems.That is, the method of (1) has a problem of low productivity causedbecause a long time is required for the curing process. That is, aproduction process of an electronic component normally proceeds in aunit of seconds whereas, in the method of (1), the curing processrequires approximately one hour and therefore components are retained(i.e., accumulated) in the curing process. This also causes a problem inthe method of (1) that, in order to deal with the retention ofcomponents, it is necessary to enlarge production facilities.

Moreover, the method of (1) has the following problem: that is,electronic components are to be left at a high temperature, andtherefore a heat load is placed on a part other than the part in whichthe one-part epoxy resin adhesive agent has been applied. From this, inthe method of (1), non-uniformity in performance may occur due todeformation. Further, the method of (1) also has a problem that a gas ofthe adhesive agent is generated by leaving the adhesive agent at thehigh temperature, and this may lower an electrical characteristic of ametal part.

In addition, the one-part epoxy resin has a problem as follows: that is,in a case where a cure-accelerating agent is mixed in order to lower acuring temperature and to improve reactivity, storage stability becomesimpaired.

In the method of (2), although a curing time is short, it is difficultto uniformly mix the two liquids. From this, there is a problem thatstable bonding quality cannot be obtained. Moreover, curing startsimmediately after the two liquids are mixed, and therefore the method of(2) has a problem that a work life is short and workability is extremelylow. Further, in a case where a coating machine is used in the method of(2) in order to improve application accuracy, there is a problem that anozzle is more likely to be clogged and a frequency of carrying outmaintenance with respect to the coating machine is high.

In the method of (3), curing can be carried out at a low temperature andin a short time. However, an acid is contained in the UV-curableadhesive agent, and the acid remains in the resin even after curing. Asa result, in a case where the UV-curable adhesive agent is applied to anelectronic component, the acid causes corrosion of the electroniccomponent. Therefore, the method of (3) has a problem that an obtainedelectronic component is to be extremely low in durability.

The method of (4) has problems that a work life is short and thereforeworkability is low, and bonding quality is not stable. Alternatively,the method of (4) also has a problem that an obtained electroniccomponent is low in durability.

Moreover, in the technique disclosed in Patent Literature 1, a cationicpolymerization initiator is used and, from this, reactivity is low andthis causes an inconvenience that physical properties of a cured productsuch as hardness are changed with time as a reaction gradually proceeds.Further, there is a concern in the technique disclosed in PatentLiterature 1 as follows: that is, in a case where metal exists aroundthe acid remaining inside, the acid may corrode a metal part around theacid.

Further, in the technique disclosed in Patent Literature 2, an ordinarycuring method by heat is used, and a heat treatment is carried out for along time, i.e., approximately one hour.

As such, the conventionally used resin composition cannot be cured in ashort time without placing a heat load on an adherend and cannot attainan object of obtaining a cured product having stable bonding quality.

The present invention is accomplished in view of the conventionalproblems, and its object is to provide (i) a resin composition withwhich curing can be carried out in a short time without placing a heatload on an adherend and from which a cured product having stable bondingquality can be obtained and (ii) a cured product of the resincomposition.

Solution to Problem

In order to attain the object, the inventors of the present inventionstudied a relation between a composition of the resin composition andenergy applied for a curing reaction. As a result, the inventors of thepresent invention found that, in each of cases where a resin compositionhaving a specific composition is irradiated with laser light and whereheat is applied in a normal curing oven, it is possible to obtain acured product in a very short time as compared with a conventional resincomposition, and a heat load on a part around a part in which the resincomposition has been applied can be reduced, and the cured productexhibits excellent durability. Based on this finding, the presentinvention has been accomplished.

That is, the resin composition in accordance with the present inventioncontains a bisphenol A epoxy resin; an encapsulated curing agentincluding a core that contains a curing agent and a shell that coversthe core; a filler; and a color material.

Advantageous Effects of Invention

The resin composition in accordance with the present invention containsa bisphenol A epoxy resin; an encapsulated curing agent including a corethat contains a curing agent and a shell that covers the core; a filler;and a color material.

From this, it is possible to carry out a curing reaction in an extremelyshort time and while significantly reducing a heat load on a part thatis around a part to which the resin composition has been applied. As aresult, the resin composition of the present invention brings about aneffect of efficiently carrying out bonding or sealing of members in anelectronic component with good quality.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically illustrating a state in which (i) a resincomposition in accordance with the present invention is applied to asurface of an adherend, (ii) a surface of another adherend is attachedonto the resin composition, and (iii) an upper surface of the anotheradherend is irradiated with laser light.

FIG. 2 is a view schematically illustrating a state in which a terminalis bonded to an adherend which is a resin molded product and theterminal is sealed, by a method in accordance with Embodiment 5.

FIG. 3 is a vertical cross-sectional view illustrating the adherendillustrated in FIG. 2 to which the terminal is bonded and sealed.

FIG. 4 is a view schematically illustrating a method for preparing anadhesive-agent-applied sample.

FIG. 5 is a view schematically illustrating amounts of warpage of a PBTplate (adherend) before and after curing.

FIG. 6 is a view illustrating results of observing a vertical crosssection of a cured product of an adhesive-agent-applied sample.

DESCRIPTION OF EMBODIMENTS

The following description will discuss embodiments of the presentinvention. In the descriptions below, the same reference numerals aregiven to components which are identical in name and in function. Suchcomponents are not repeatedly described in detail.

Embodiment 1

A resin composition in accordance with Embodiment contains a bisphenol Aepoxy resin; an encapsulated curing agent including a core that containsa curing agent and a shell that covers the core; a filler; and a colormaterial.

(1. Bisphenol A Epoxy Resin)

The bisphenol A epoxy resin is preferably an epoxy resin that is in aform of liquid at around a room temperature (e.g., 25° C.). As laterdescribed, the bisphenol A epoxy resin is cured by reaction with acuring agent contained in an encapsulated curing agent when the resincomposition is directly and/or indirectly irradiated with energy such aslaser light or an infrared ray and the encapsulated curing agent iscleaved. By considering that an obtained cured product may be used in anelectronic component, the bisphenol A epoxy resin is used in the presentinvention in order to secure resistance to high temperature.

Examples of the bisphenol A epoxy resin specifically encompass bisphenolA diglycidyl ether, bisphenol A ethylene oxide 2-mole adduct diglycidylether, bisphenol A-1,2-propylene oxide 2-mole adduct diglycidyl ether,hydrogenated bisphenol A diglycidyl ether, tetrabromobisphenol Adiglycidyl ether, and the like. These compounds can be used alone or incombination of two or more of these.

Among these, in view of excellent resistance to high temperature of acured product, the epoxy resin is more preferably bisphenol A diglycidylether or hydrogenated bisphenol A diglycidyl ether.

(2. Encapsulated Curing Agent)

In Embodiment 1, it is important to use the encapsulated curing agentwhich includes (i) the core that contains the curing agent and (ii) theshell that covers the core. The resin composition in accordance with thepresent invention contains the encapsulated curing agent, and thereforeit is possible to finish a curing reaction of the epoxy resin in anextremely short time by irradiation with laser light. Moreover, forexample, in a case where curing is carried out by irradiation with aninfrared ray, it is possible to finish the curing in a shorter time thana case where a conventionally known one-part epoxy resin composition isused.

The curing agent contained in the core is preferably one or more curingagents selected from the group consisting of an amine compound, animidazole compound, and a thiol compound.

(2-1. Amine Compound)

The amine compound can be an ordinarily used amine curing agent such asan amine adduct curing agent, a modified polyamine curing agent, analiphatic polyamine curing agent, a heterocyclic polyamine curing agent,an alicyclic polyamine curing agent, an aromatic amine curing agent, apolyamideamine curing agent, a ketimine curing agent, a urethaneaminecuring agent, or the like. These amine curing agents can be used aloneor in combination of two or more of these. In a case where the aminecuring agents are used in combination, ratios of the amine curing agentscan be arbitrarily determined. Among these, from the viewpoint ofmoderate reactivity and stability, it is preferable to use an aminecuring agent which is a mixture containing a low-molecular aminecompound (a1) and an amine adduct.

Note, however, that the low-molecular amine compound (a1) can be usedalone. Moreover, low-molecular amine compounds (a1) exemplified belowcan be used alone or in combination of two or more of those. In a casewhere the low-molecular amine compounds (a1) are used in combination,ratios of the low-molecular amine compounds (a1) can be arbitrarilydetermined.

Examples of the low-molecular amine compound (a1) encompass a compoundwhich has at least one primary amino group and/or secondary amino groupand does not have a tertiary amino group; a compound which has at leastone tertiary amino group and at least one active hydrogen group; and thelike.

Examples of the compound which has at least one primary amino groupand/or secondary amino group and does not have a tertiary amino groupencompass primary amines having no tertiary amino group such asmethylamine, ethylamine, propylamine, butylamine, ethylenediamine,propylenediamine, hexamethylenediamine, diethylenetriamine,triethylenetetramine, ethanolamine, propanolamine, cyclohexylamine,isophoronediamine, aniline, toluidine, diaminodiphenylmethane, anddiaminodiphenyl sulfone; secondary amines having no tertiary amino groupsuch as dimethylamine, diethylamine, dipropylamine, dibutylamine,dipentylamine, dihexylamine, dimethanolamine, diethanolamine,dipropanolamine, dicyclohexylamine, piperidine, piperidone,diphenylamine, phenylmethylamine, and phenylethylamine.

Examples of the compound which has at least one tertiary amino group andat least one active hydrogen group encompass aminoalcohols such as2-dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol,1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol,1-butoxymethyl-2-dimethylaminoethanol, methyldiethanolamine,triethanolamine, and N-β-hydroxyethylmorpholine; aminophenols such as2-(dimethylaminomethyl)phenol, and2,4,6-tris(dimethylaminomethyl)phenol; tertiary aminoamines such asdimethylaminopropylamine, diethylaminopropylamine,dipropylaminopropylamine, dibutylaminopropylamine,dimethylaminoethylamine, diethylaminoethylamine,dipropylaminoethylamine, dibutylaminoethylamine, N-methylpiperazine,N-aminoethylpiperazine, and diethylaminoethylpiperazine; aminomercaptanssuch as 2-dimethylaminoethanethiol, 2-mercaptobenzoimidazole,2-mercaptobenzothiazole, 2-mercaptopyridine, and 4-mercaptopyridine;aminocarboxylic acids such as N,N-dimethylaminobenzoic acid,N,N-dimethylglycine, nicotinic acid, isonicotinic acid, and picolinicacid; and aminohydrazides such as N,N-dimethylglycine hydrazide,nicotinic acid hydrazide, and isonicotinic acid hydrazide. The compoundwhich has at least one tertiary amino group and at least one activehydrogen group is preferably one or more compounds selected from thegroup consisting of the above compounds.

The amine adduct can be used alone or can be mixed with thelow-molecular amine compound (a1) as above described. Examples of theamine adduct encompass compounds which have an amino group and areobtained by reaction of an amine compound (a2) and one or more compoundsselected from the group consisting of a carboxylic acid compound, asulfonic acid compound, a urea compound, an isocyanate compound, and anepoxy resin (e1).

The amine compound (a2) can be any of the amine compounds aboveexemplified as the low-molecular amine compound (a1).

Among the amine adducts, it is particularly preferable to employ theamine adduct that is obtained by reaction of the epoxy resin (e1) andthe amine compound (a2). The amine adduct that is obtained by reactionof the epoxy resin (e1) and the amine compound (a2) is preferable alsobecause an unreacted amine compound (a2) can be used as a low-molecularamine compound (a1).

Examples of the carboxylic acid compound encompass succinic acid, adipicacid, sebacic acid, phthalic acid, dimer acid, and the like. Examples ofthe sulfonic acid compound encompass ethanesulfonic acid,p-toluenesulfonic acid, and the like. Examples of the urea compoundencompass urea, methylurea, dimethylurea, ethylurea, t-butylurea, andthe like.

Examples of the isocyanate compound encompass aliphatic diisocyanate,alicyclic diisocyanate, aromatic diisocyanate, aliphatic triisocyanate,polyisocyanate, and the like.

Examples of aliphatic diisocyanate encompass ethylenediisocyanate,propylenediisocyanate, butylenediisocyanate, hexamethylenediisocyanate,trimethylhexamethylenediisocyanate, and the like.

Examples of alicyclic diisocyanate encompass isophoronediisocyanate,4,4′-dicyclohexylmethanediisocyanate, norbornanediisocyanate,1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane,1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane, and the like.

Examples of aromatic diisocyanate encompass tolylenediisocyanate,4,4′-diphenylmethanediisocyanate, xylenediisocyanate,1,5-naphthalenediisocyanate, and the like.

Examples of aliphatic triisocyanate encompass1,6,11-undecanetriisocyanate, 1,8-diisocyanate-4-isocyanatemethyloctane,1,3,6-triisocyanatemethylhexane, and the like.

Examples of polyisocyanate encompasspolymethylenepolyphenylpolyisocyanate, polyisocyanate derived from thediisocyanate compound, and the like. Examples of polyisocyanate derivedfrom diisocyanate encompass isocyanurate type polyisocyanate, buret typepolyisocyanate, urethane type polyisocyanate, allophanate typepolyisocyanate, carbodiimide type polyisocyanate, and the like.

Examples of the epoxy resin (e1) encompass a monoepoxy compound, apolyvalent epoxy compound, a mixture thereof, and the like.

Examples of the monoepoxy compound encompass butyl glycidyl ether, hexylglycidyl ether, phenyl glycidyl ether, allyl glycidyl ether,para-tert-butylphenyl glycidyl ether, ethylene oxide, propylene oxide,paraxylyl glycidyl ether, glycidyl acetate, glycidyl butyrate, glycidylhexoate, glycidyl benzoate, and the like.

The polyvalent epoxy compound encompass bisphenol type epoxy resinswhich are obtained by glycidylating bisphenols such as bisphenol A,bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A,tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S,tetrabromobisphenol A, tetrachlorobisphenol A, and tetrafluorobisphenolA; epoxy resins which are obtained by glycidylating other dihydricphenols such as biphenol, dihydroxynaphthalene, and9,9-bis(4-hydroxyphenyl)fluorene; epoxy resins which are obtained byglycidylating trisphenols such as 1,1,1-tris(4-hydroxyphenyl)methane and4,4-(1-(4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl)ethylidene)bisphenol;epoxy resins which are obtained by glycidylating tetrakisphenols such as1,1,2,2,-tetrakis(4-hydroxyphenyl)ethane; novolac type epoxy resinswhich are obtained by glycidylating novolacs such as phenol novolac,cresol novolac, bisphenol A novolac, brominated phenol novolac, andbrominated bisphenol A novolac; an epoxy resin which is obtained byglycidylating a polyhydric phenol; aliphatic ether type epoxy resinswhich are obtained by glycidylating polyhydric alcohols such as glycerinand polyethylene glycol; ether ester type epoxy resins which areobtained by glycidylating hydroxycarboxylic acids such as p-hydroxybenzoic acid and β-oxynaphthoic acid; ester type epoxy resins which areobtained by glycidylating polycarboxylic acids such as phthalic acid andterephthalic acid; glycidyl type epoxy resins such as glycidylatedproducts of amine compounds such as 4,4-diaminodiphenylmethane andm-aminophenol, and an amine type epoxy resin such astriglycidylisocyanurate; an alicyclic epoxide such as3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate.

As the amine curing agent, an aromatic amine curing agent can also besuitably used as above described. Examples of the aromatic amine curingagent encompass aromatic polyamines such as orthophenylenediamine,methaphenylenediamine, paraphenylenediamine, diaminotoluene,N,N-dimethyl-para-phenylenediamine, N,N-diethyl-3,4-tolylenediamine,benzidine, tetramethyldiaminodiphenylmethane,tetraethyldiaminodiphenylmethane, diaminodiphenylamine, diaminostilbene,diaminodiphenylmethane, diaminodiphenyl sulfone, m-xylenediamine, andxylylenediamine.

The aromatic polyamines can be used alone or in combination of two ormore of these. In a case where the aromatic polyamines are used incombination, ratios of the aromatic polyamines can be arbitrarilydetermined.

(2-2. Imidazole Compound)

The imidazole compound is preferably one or more compounds selected fromthe group consisting of imidazoles such as 2-methylimidazole,2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole,2-phenylimidazole, 1-aminoethyl-2-methylimidazole,1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole,1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole,1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, and1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole; and imidazolinessuch as 1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline,1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2-methylimidazoline,2,4-dimethylimidazoline, 2-ethylimidazoline,2-ethyl-4-methylimidazoline, 2-benzylimidazoline, 2-phenylimidazoline,2-(ortho-tolyl)-imidazoline, tetramethylene-bis-imidazoline,1,1,3-trimethyl-1,4-tetramethylene-bis-imidazoline,1,3,3-trimethyl-1,4-tetramethylene-bis-imidazoline,1,1,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline,1,3,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline,1,2-phenylene-bis-imidazoline, 1,3-phenylene-bis-imidazoline,1,4-phenylene-bis-imidazoline, and1,4-phenylene-bis-4-methylimidazoline.

The imidazole compounds can be used alone or in combination of two ormore of these. In a case where the imidazole compounds are used incombination, ratios of the imidazole compounds can be arbitrarilydetermined.

(2-3. Thiol Compound)

Examples of the thiol compound encompass3-methoxybutyl(3-mercaptobutyrate), 2-methylhexyl(3-mercaptobutyrate),ethylene glycol bis(2-mercaptoisobutyrate), ethylene glycolbis(3-mercaptobutyrate), 1,2-propylene glycol(3-mercaptobutyrate),trimethylolpropane tris(3-mercaptobutyrate),tridecyl(3-mercaptobutyrate), 1,2-propylene glycolbis(2-mercaptoisobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane,pentaerythritol tetrakis(3-mercaptobutyrate),1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione,1,3,5-trimercaptomethylbenzene, bisphenol A bis(3-mercaptobutyrate), andtriphenolmethane tris(3-mercaptobutyrate). Note, however, that the thiolcompound used in the present invention is not limited to these.

The thiol compounds can be used alone or in combination of two or moreof these. In a case where the thiol compounds are used in combination,ratios of the thiol compounds can be arbitrarily determined.

Among these, ethylene glycol bis(3-mercaptobutyrate), trimethylolpropanetris(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, and/orpentaerythritol tetrakis(3-mercaptobutyrate) can be preferably usedbecause these compounds can bring about a greater cure-acceleratingeffect even in a small amount thereof. These compounds can be used aloneor in combination of two or more of these as a mixture.

The thiol compound used in the present invention can be easily obtainedas a commercially available product. Examples of the thiol compound thatcan be obtained as a commercially available product encompass ethyleneglycol bis(3-mercaptobutyrate) (product name: EGTP, manufactured by YodoKagaku Co., Ltd.), trimethylolpropane tris(3-mercaptobutyrate) (productname: TMTP, manufactured by Yodo Kagaku Co., Ltd.),1,4-bis(3-mercaptobutyryloxy)butane (product name: BDTP, manufactured byYodo Kagaku Co., Ltd.), pentaerythritol tetrakis(3-mercaptobutyrate)(product name: Karenz MT PE 1, manufactured by Showa Denko K.K.), andthe like.

(2-4. Shell)

The shell of Embodiment 1 covers the core and includes at least a firstshell. The first shell of Embodiment 1 preferably directly covers asurface of the core, has a urea group, and does not have an ester bond.It is more preferable that the first shell has a urea group, a buretgroup, and a urethane group and does not have an ester group.

In a case where a reaction product has a urea group, solvent resistanceof an encapsulated curing agent tends increase. Further, in a case wherethe reaction product additionally has a buret group and a urethanegroup, the solvent resistance favorably tends to further increase.

On the other hand, in a case where the reaction product has an esterbond, the first shell is impaired due to hydrolysis reaction caused bythe ester bond in a high humidity state, and this may reduce storagestability and humidity resistance of the encapsulated curing agent andphysical properties of a cured product that is obtained by curing theepoxy resin composition in accordance with the present invention thatcontains the encapsulated curing agent.

The first shell is preferably an amine curing agent contained in thecore; a reaction product of an epoxy resin curing agent (h1) (that iscompatible with an amine curing agent) and an isocyanate compound; areaction product of an amine curing agent and an isocyanate compound; areaction product of an active hydrogen compound and an isocyanatecompound; or the like. In view of good solvent resistance, it isparticularly preferable that the first shell is a reaction product of anamine curing agent and an isocyanate compound.

Here, examples of the epoxy resin curing agent (h1) that is compatiblewith an amine curing agent encompass acid anhydride curing agents suchas phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalicanhydride, and methylnadic acid; phenol curing agents such as phenolnovolac, cresol novolac, and bisphenol A novolac; mercaptan curing agentsuch as propylene glycol modified polymercaptan, thiogluconic acid esterof trimethylolpropane, and a polysulfide resin; a boron halide saltcuring agent such as ethylamine salt of trifluoroborane; a quaternaryammonium salt curing agent such as phenol salt of1,8-diazabicyclo(5,4,0)-undeca-7-en; a urea curing agent such as3-phenyl-1,1-dimethylurea; phosphine curing agents such astriphenylphosphine and tetraphenylphosphoniumtetraphenyl borate; and thelike. As the isocyanate compound, it is possible to suitably use any ofthe isocyanate compounds exemplified as a raw material of the amineadduct that is contained in the core.

The active hydrogen compound can be water; a compound having at leastone primary amino group and/or secondary amino group; a compound whichhas at least one hydroxyl group and does not contain an ester group inits structure; or the like. These compounds can be used alone or incombination of two or more of these.

Examples of the compound having at least one primary amino group and/orsecondary amino group encompass aliphatic amine, alicyclic amine,aromatic amine, and the like.

Examples of aliphatic amine encompass alkylamines such as methylamine,ethylamine, propylamine, butylamine, and dibutylamine; alkylenediaminessuch as ethylenediamine, propylenediamine, butylenediamine, andhexamethylenediamine; polyalkylenepolyamines such as diethylenetriamine,triethylenetetramine, and tetraethylenepentamine;polyoxyalkylenepolyamines such as polyoxypropylenediamine andpolyoxyethylenediamine; and the like.

Examples of alicyclic amine encompass cyclopropylamine, cyclobutylamine,cyclopentylamine, cyclohexylamine, isophoronediamine, and the like.

Examples of aromatic amine encompass aniline, toluidine, benzylamine,naphthylamine, diaminodiphenylmethane, diaminodiphenyl sulfone, and thelike.

Examples of the compound having at least one hydroxyl group encompass analcohol compound, a phenol compound, and the like.

Examples of the alcohol compound encompass monoalcohols such asmethylalcohol, propyl alcohol, butyl alcohol, amyl alcohol,hexylalcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decylalcohol, undecyl alcohol, lauryl alcohol, dodecyl alcohol, stearylalcohol, eicosyl alcohol, allyl alcohol, crotyl alcohol, propargylalcohol, cyclopentanol, cyclohexanol, benzyl alcohol, cinnamyl alcohol,ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,ethylene glycol monoethyl ether, and diethylene glycol monobutyl; andpolyhydric alcohols such as ethylene glycol, polyethylene glycol,propylene glycol, polypropylene glycol, 1,3-butandiol, 1,4-butandiol,hydrogenated bisphenol A, neopentyl glycol, glycerin,trimethylolpropane, and pentaerythritol.

The polyhydric alcohols also encompass a compound which has, in onemolecule, two or more secondary hydroxyl groups and is obtained by areaction between (i) a compound having at least one epoxy group and (ii)one or more compounds selected from the group consisting of a compoundhaving at least one hydroxyl group, a compound having at least onecarboxyl group, a compound having at least one primary or secondaryamino group, and a compound having at least one mercapto group. Thesealcohol compounds can be any of primary, secondary, and tertiaryalcohols.

Examples of the phenol compound encompass monophenols such as carbolicacid, cresol, xylenol, carvacrol, thymol, and naphthol; and polyhydricphenols such as catechol, resorcin, hydroquinone, bisphenol A, bisphenolF, pyrogallol, and phloroglucine.

The compound having at least one hydroxyl group is preferably any of thepolyhydric alcohols and the polyhydric phenols, particularly preferablyany of the polyhydric alcohols.

The shell of Embodiment 1 preferably includes a second shell that isprovided on a surface of the first shell and is made of a reactionproduct obtained from a reaction between the first shell and an epoxyresin (e2). The second shell is preferably a reaction product that isobtained from a reaction between the first shell and the epoxy resin(e2). The reaction product can be obtained by, for example, (i) a methodin which particles serving as a starting material for forming a core aredispersed in a dispersion medium, and a material for forming a shell isadded to the dispersion medium so as to precipitate the reaction producton the starting material particles or (ii) a method in which a rawmaterial for forming a shell is added to a dispersion medium and a shellforming material is generated on surfaces of starting material particleswhich surfaces serve as a reaction field.

Examples of the dispersion medium encompass hydrocarbons such asbenzene, toluene, xylene, cyclohexane, mineral spirit, and naphtha;ketones such as acetone, methyl ethyl ketone, and methyl isobutylketone; esters such as ethyl acetate, n-butyl acetate, and propyleneglycol monomethyl ethyl ether acetate; alcohols such as methanol,isopropanol, n-butanol, butylcellosolve, and butyl Carbitol; a solventsuch as water; phthalic acid diester plasticizers such as dibutylphthalate and di(2-ethylhexyl)phthalate; an aliphatic dibasic acid esterplasticizer such as di(2-ethylhexyl)adipate; a triester phosphateplasticizer such as tricresyl phosphate; a glycol ester plasticizer suchas polyethylene glycol ester: and the like.

As the epoxy resin (e2), it is possible to suitably use the polyvalentepoxy compounds exemplified as the epoxy resin (e1) which is a rawmaterial of the amine adduct contained in the core. The epoxy resins(e2) can be used alone or in combination of two or more.

The epoxy resin (e2) is preferably (i) identical with an epoxy resin(e3) that is contained in a curing agent composition for a masterbatchtype epoxy resin or (ii) a part of a mixture in a case where the epoxyresin (e3) is the mixture, because a microencapsulated epoxy resincuring agent having excellent storage stability and solvent resistanceis more likely to be obtained.

As the epoxy resin (e3), it is possible to use the polyvalent epoxycompounds exemplified as the epoxy resin (e1) which is a raw material ofthe amine adduct contained in the core. Those epoxy resins can be usedalone or in combination. Among those, from the viewpoint of adhesivenessand resistance to high temperature of a cured product to be obtained, anepoxy resin obtained by glycidylating a polyhydric phenol is preferable,a bisphenol type epoxy resin is more preferable, a glycidylated productof bisphenol A and a glycidylated product of bisphenol F are furtherpreferable.

(2-5. Method for Preparing Encapsulated Curing Agent, etc.)

A method for covering the surface of the core with the first shell canbe, for example, (i) a method in which a first shell is dissolved andsolubility of the first shell is lowered in a dispersion medium, inwhich the core is dispersed, and thus the first shell is precipitated onthe surface of the core, (ii) a method in which a shell-forming reactionis carried out in a dispersion medium in which the core is dispersed,and thus a shell is precipitated on the surface of the core, or (iii) amethod in which a shell is generated on the surface of the core whichsurface serves as a reaction field.

The method for covering a surface of the first shell with the secondshell can be, for example, a method in which the core covered with thefirst shell is caused to react with an epoxy resin at 20° C. to 80° C.for approximately 2 hours to 8 hours. Note that the encapsulated curingagent can be prepared as above described or a commercially availableproduct can be used.

An average particle diameter of the encapsulated curing agent ispreferably 1 μm or more and 100 μm or less, and more preferably 1 μm ormore and 10 μm or less. In a case where the average particle diameter issmaller than 1 μm, the shell is cleaved when the resin composition inaccordance with the present invention is mixed with another component,and accordingly a curing reaction may unfavorably start before energy isapplied. In a case where the average particle diameter is larger than100 μm, such a case is not preferable because (i) reactivity of theencapsulated curing agent may decrease and (ii) it may become difficultto mix a filler because the average particle diameter approaches aparticle diameter of the filler and the encapsulated curing agent andthe filler interfere with each other.

In a case where the average particle diameter is 1 μm or more and 10 μmor less, such a case is more preferable because (i) reactivity of theencapsulated curing agent increases and (ii) it becomes easy to mix afiller because the average particle diameter is smaller than a particlediameter of the filler and the encapsulated curing agent and the fillerare less likely to interfere with each other.

Note that, in this specification, the term “average particle diameter”indicates a median diameter, and the term “particle diameter” indicatesa Stokes' diameter measure by a light-scattering method with use of aparticle size distribution meter (laser diffraction/scatter particlediameter distribution meter LA-750 manufactured by Horiba, Ltd.).

(3. Filler)

The filler is used to improve rigidity and heat stability of the resincomposition in accordance with the present invention. From this, in acase where the resin composition in accordance with the presentinvention is used for bonding, it is possible to achieve firm bondingwith high resistance to high temperature.

As the filler, it is possible to suitably use calcium carbonate, silica(which can be either fused silica or crystalline silica), mica, talc,glass beads, alumina, silicon nitride, calcium silicate, barium sulfate,aluminium hydroxide, magnesium hydroxide, or the like. These inorganicfillers can be used alone or in combination of two or more of these. Ina case where the inorganic fillers are used in combination, ratios ofthe inorganic fillers can be arbitrarily determined.

Among these, the filler is preferably one or more fillers selected fromthe group consisting of calcium carbonate, silica, mica, talc, and glassbeads because these can bring about good rigidity and heat stability.

Further, the filler is preferably one or more fillers selected from thegroup consisting of fused silica, crystalline silica, and glass beadsbecause these are excellent in effect of improving rigidity of the resincomposition in accordance with the present invention and inlight-transmitting property.

The filler which is excellent in light-transmitting property isadvantageous in a case where the resin composition in accordance withthe present invention is used as an adhesive agent and the resincomposition in accordance with the present invention is sandwichedbetween a surface of one adherend and a surface of another adherend thatis different from the one adherend, that is, in a case where the resincomposition in accordance with the present invention is sandwichedbetween surfaces of respective different adherends in order to bond thedifferent adherends together.

That is, in such a case, the resin composition in accordance with thepresent invention is to be irradiated with an energy beam (e.g., laserlight, infrared ray) that has passed through the adherend, and thus theresin composition is indirectly irradiated with the energy beam. In thiscase, the filler having an excellent light-transmitting property cangreatly inhibit reflection of light as compared with a normal whitefiller, and it is therefore possible to more efficiently proceed with acuring reaction.

(4. Color Material)

The color material is contained in the resin composition in accordancewith the present invention so that the resin composition can efficientlyabsorb heat of an energy beam such as laser light or an infrared ray anda curing reaction proceeds more efficiently. The color material ispreferably one or more selected from the group consisting of aninorganic pigment, an organic pigment, and a dye.

Concrete examples of the inorganic pigment which can be suitably usedencompass mars black, ivory black, peach black, lampblack, carbon black,titanium dioxide, white lead, lithopone, red lead, cobalt violet, lightred, cobalt blue, cerulean blue, ultramarine blue, Prussian blue, cobaltgreen, chromium oxide green, chrome yellow, zinc yellow, iron oxidecompounds (such as iron red, yellow iron oxide, black iron oxide),chrome oxide compounds (such as chrome oxide (III), chrome oxide (IV),viridian), copper compounds (such as verdigris, mountain green), and thelike.

The inorganic pigments can be used alone or in combination of two ormore of these. In a case where the inorganic pigments are used incombination of two or more, ratios of the inorganic pigments can bearbitrarily determined. Among these, the inorganic pigment is morepreferably a black-based pigment, a red-based pigment, a blue-basedpigment, a green-based pigment, and a yellow-based pigment, because oftheir excellent heat-absorbing property.

Concrete examples of the organic pigment which can be suitably usedencompass lake red c, permanent red 2b, naphthol red, perylene,perinone, indigoid, Cromophtal red, quinacridone, anthraquinone,diketopyrrolopyrrole, alizarin lake, isoindolinone, isoindolin,azomethine, anthraquino, anthrone, xanthene, first yellow, disazoyellow, Cromophtal yellow, nickel azo yellow, benzimidazolone yellow,quinoline yellow lake, rhodamine lake, phthalocyanine, brilliant carmine6b, phthalocyanine compounds (such as phthalocyanine, phthalocyaninegreen, phthalocyanine blue), dioxazine, and the like.

The organic pigments can be used alone or in combination of two or moreof these. In a case where the organic pigments are used in combinationof two or more, ratios of the organic pigments can be arbitrarilydetermined. Among these, the organic pigment is more preferably ablack-based pigment, a red-based pigment, a blue-based pigment, agreen-based pigment, and a yellow-based pigment, because of theirexcellent heat-absorbing property.

Concrete examples of the dye which can be suitably used encompass adirect dye, an acid dye, a basic dye, a disperse dye, a reactive dye, amordant dye, an acid mordant dye, and the like.

The dyes can be used alone or in combination of two or more of these. Ina case where the dyes are used in combination of two or more, ratios ofthe dyes can be arbitrarily determined. Among these, the dye is morepreferably a black-based dye, a red-based dye, a blue-based dye, agreen-based dye, and a yellow-based dye, because of their excellentheat-absorbing property.

The color material is preferably one or more color materials selectedfrom the group consisting of carbon black, and a pigment and a dye whichare different from carbon black. Carbon black is preferable becausecarbon black contained in the resin composition in accordance with thepresent invention allows a heat-absorbing property of the resincomposition to be greatly improved, and carbon black is inexpensive andis high in versatility.

Meanwhile, carbon black is more likely to absorb heat of the surface ofthe resin composition. Therefore, carbon black is particularly suitablyused in a case where a film which has been obtained by applying theresin composition and has a relatively small film thickness is to bequickly cured. The film thickness is preferably less than 300 μm, morepreferably 100 μm or less, and particularly preferably 50 μm or less. Alower limit of the film thickness is not particularly limited, providedthat the film has effective thickness to be applied with the resincomposition, and only needs to be larger than 0 μm.

The film thickness can be adjusted, for example, with use of aconventionally known thickness gauge as later described in Examples.

As such, in a case where the film thickness of the film obtained byapplying the resin composition is less than 300 μm, carbon black can beparticularly suitably used, and it is most preferable that carbon blackis used alone as a color material. Note that, even in a case where thefilm thickness is less than 300 μm, it is possible to employ a pigmentand/or a dye different from carbon black. Alternatively, in a case wherethe film thickness is less than 300 μm, it is possible to use one ormore color materials selected from the group consisting of carbon black,and a pigment and a dye which are different from carbon black. That is,a pigment and/or a dye which are not carbon black can be used incombination with carbon black.

Note that the pigment other than carbon black can be a pigment which isincluded in the above described inorganic pigments except carbon blackand can be the organic pigment.

In a case where the film thickness is 300 μm or more and only carbonblack is used as the color material, an energy beam such as laser lightor an infrared ray may not sufficiently reach a deep part of the film.However, even in such a case, it is possible to cause the energy beam toreach the deep part of the film by employing, instead of carbon black, apigment and/or a dye which are not carbon black or by using such apigment and/or a dye in combination with carbon black. In this case, thefilm thickness is preferably 300 μm or more and 5 mm or less.

In a case where the film thickness is 300 μm or more and 5 mm or less,it is preferable to employ, instead of carbon black, a pigment and/or adye which are not carbon black as the color material, in order for anenergy beam such as laser light or an infrared ray to sufficiently reachthe deep part of the film. Among those, it is more preferable to use apigment different from carbon black. The pigment different from carbonblack is preferably one or more compounds selected from the groupconsisting of an iron oxide compound, a phthalocyanine compound, achrome oxide compound, and a copper compound.

(5. Contained Amounts of Components, Method for Preparing ResinComposition in Accordance with the Present Invention)

An amount of the bisphenol A epoxy resin contained in the resincomposition in accordance with the present invention can be changed asappropriate in accordance with a purpose of use. By taking intoconsideration resistance to high temperature of a cured product, acontained amount of the bisphenol A epoxy resin is preferably in a rangebetween not less than 10% by weight and not more than 99% by weight,more preferably in a range between not less than 20% by weight and notmore than 95% by weight, and particularly preferably in a range betweennot less than 30% by weight and not more than 90% by weight, relative to100% by weight of the resin composition.

In order to sufficiently proceed with a curing reaction, an amount ofthe encapsulated curing agent contained in the resin composition inaccordance with the present invention is preferably not less than 0.1parts by weight and not more than 70 parts by weight, more preferablynot less than 1 part by weight and not more than 60 parts by weight, andparticularly preferably not less than 3 parts by weight and not morethan 50 parts by weight, relative to 100 parts by weight of thebisphenol A epoxy resin.

An amount of the filler contained in the resin composition in accordancewith the present invention is preferably not less than 5 parts by weightand not more than 80 parts by weight, more preferably not less than 10parts by weight and not more than 70 parts by weight, particularlypreferably not less than 20 parts by weight and not more than 60 partsby weight, relative to 100 parts by weight of the bisphenol A epoxyresin. In a case where a contained amount of the filler is less than 5parts by weight, strength of the resin composition becomes unfavorablyinsufficient. In a case where the contained amount of the filler is morethan 80 parts by weight, viscosity of the resin composition becomesexcessively high, and this unfavorably makes it difficult to cause acuring reaction.

In order to cause the resin composition to efficiently absorb an energybeam such as laser light or an infrared ray, an amount of the colormaterial contained in the resin composition is preferably not less than0.01 parts by weight and not more than 20 parts by weight, relative to100 parts by weight of the bisphenol A epoxy resin contained in theresin composition.

In a case where the color material is carbon black, a contained amountof the carbon black is preferably not less than 0.01 parts by weight andnot more than 20 parts by weight, more preferably not less than 0.5parts by weight and not more than 10 parts by weight, particularlypreferably not less than 1 part by weight and not more than 7 parts byweight, relative to 100 parts by weight of the bisphenol A epoxy resin.

The carbon black is particularly advantageous in a case where aheat-absorbing property of the resin composition whose film thickness isrelatively small is improved and curing of the resin composition isfacilitated. Therefore, it is particularly preferable to use carbonblack in a case where a film thickness of a film obtained by applyingthe resin composition is less than 300 μm. Moreover, in a case where thefilm thickness is less than 300 μm, it is most preferable to use carbonblack alone as the color material.

In a case where energy is applied to the resin composition in accordancewith the present invention, carbon black allows a surface layer part ofa film obtained by applying the resin composition to have an excellentheat-absorbing property. Therefore, in a case where the film thicknessis relatively large (i.e., 300 μm or more), it is sometimes difficult tocause an energy beam to reach a deep part of the film. Meanwhile, in acase where the film thickness is less than 300 μm, a curing reaction canbe extremely efficiently carried out based on the heat-absorbingproperty.

In Examples described later, it has been confirmed that extremelyexcellent curing reactivity can be achieved in a case where a containedamount of carbon black is not less than 1 part by weight and not morethan 7 parts by weight relative to 100 parts by weight of the bisphenolA epoxy resin and the resin composition is irradiated with an infraredray or laser light.

A contained amount of the pigment and/or dye different from carbon blackin the resin composition is preferably not less than 5 parts by weightand not more than 20 parts by weight, more preferably not less than 6parts by weight and not more than 18 parts by weight, and particularlypreferably not less than 7 parts by weight and not more than 17 parts byweight, relative to 100 parts by weight of the bisphenol A epoxy resincontained in the resin composition.

The pigment and/or dye different from carbon black is particularlyadvantageous in a case of causing an energy beam such as laser light oran infrared ray to sufficiently reach a deep part of the resincomposition which has a relatively large film thickness. Therefore, thepigment and/or dye different from carbon black is particularlypreferably used in a case where a film thickness of a film obtained byapplying the resin composition is 300 μm or more and 5 mm or less.

Note that, in a case where one or more color materials selected from thegroup consisting of carbon black and the pigment and dye different fromcarbon black are used in combination, ratios of the color materialscannot be determined automatically, and can be adjusted so that intendedcuring can be carried out.

The resin composition in accordance with the present invention cancontain the bisphenol A epoxy resin, the encapsulated curing agent, thefiller, and the color material so that a ratio of these becomes 100% byweight. Alternatively, the resin composition in accordance with thepresent invention can further contain other components such as a flameretardant and a curing assistant agent. Contained amounts of the othercomponents will be described later.

A method for preparing the resin composition in accordance with thepresent invention is not limited to a particular one. For example, theresin composition in accordance with the present invention can beprepared by a method in which the epoxy resin, the encapsulated curingagent, the filler, and the color material and, according to need, othercomponents are put in a container and mixed, and are subsequentlystirred with use of a commercially available planetary centrifugalmixer.

(6. Flame Retardant)

The resin composition in accordance with the present invention cancontain one or more flame retardants selected from the group consistingof a bromine flame retardant, a phosphorus flame retardant, a nitrogenflame retardant, a chlorine flame retardant, an antimony compound flameretardant, an aluminium hydroxide flame retardant, and a magnesiumhydroxide flame retardant. In a case where the flame retardants are usedin combination, ratios of the flame retardants can be arbitrarilydetermined.

In a case where the flame retardant is contained in the resincomposition, it is possible to inhibit excessive heat from beinggenerated from the surface of the resin composition, and this makes itpossible to inhibit splash-out during a curing reaction.

Examples of the bromine flame retardant encompass tetrabromobisphenol A,tetrabromobenzene, hexabromobenzene, tribromophenol, andhexabromocyclodecane.

Examples of the phosphorus flame retardant encompass red phosphorus,triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyldiphenyl phosphate, 2-ethylhexyldiphenyl phosphate,t-butylphenyldiphenyl phosphate, bis-(t-butylphenyl)phenyl phosphate,tris-(t-butylphenyl) phosphate, isopropylphenyldiphenyl phosphate,bis-(isopropylphenyl)diphenyl phosphate, tris-(isopropylphenyl)phosphate, resorcinol bis-diphenyl phosphate, resorcinol bis-dixylenylphosphate, and bisphenol A bis-diphenyl phosphate.

Examples of the nitrogen flame retardant encompass melaminecyanurate,guanidine sulfamate, guanidine phosphate, guanylurea phosphate, andmelamine phosphate.

Examples of the chlorine flame retardant encompass chlorinated paraffinand perchloropentacyclodecane.

Examples of the antimony compound flame retardant encompass antimonytrioxide, antimony pentoxide, and trisodium antimonate.

An example of the aluminium hydroxide flame retardant encompassesaluminium hydroxide.

An example of the magnesium hydroxide flame retardant encompassesmagnesium hydroxide.

It is preferable that the flame retardant is contained, in 100 parts byweight of the resin composition, in an amount of not less than 1 part byweight and not more than 50 parts by weight.

(7. Curing Assistant Agent)

The resin composition in accordance with the present invention cancontain one or more curing assistant agents selected from the groupconsisting of an amine compound, an imidazole compound, a thiolcompound, an acid anhydride compound, and a thermal acid generatingagent. In a case where the curing assistant agents are used incombination, ratios of the curing assistant agents can be arbitrarilydetermined. The curing assistant agent contained in the resincomposition makes it possible to further facilitate a curing reaction.Note that, in this specification, the curing assistant agent means acompound that is used in combination with the encapsulated curing agentand facilitates a curing reaction caused by the encapsulated curingagent.

An amount of the curing assistant agent contained in the resincomposition in accordance with the present invention is preferably notless than 1 part by weight and not more than 60 parts by weight,relative to 100 parts by weight of the resin composition.

(7-1. Amine Compound)

It is preferable that the amine compound serving as the curing assistantagent is stable in a mixed system with an epoxy resin at around a roomtemperature and serves, by being subjected to heat treatment at 80° C.or higher and 120° C. or lower, as a curing agent by which a curedproduct having a high heat distortion temperature can be obtained.

From these viewpoints, the amine compound is preferably a denaturedaliphatic polyamine compound. The denatured aliphatic polyamine compoundis preferably a compound which (i) is a solid that is insoluble in ageneral liquid epoxy resin at around a room temperature but (ii) becomessoluble by being heated so as to perform its intrinsic function.

The denatured aliphatic polyamine compound only needs to be a reactionproduct obtained by reacting at least an amine compound with anisocyanate compound. In general, a compound called a denatured productof aliphatic polyamine is encompassed in the denatured aliphaticpolyamine compound.

Specifically, examples of the denatured aliphatic polyamine compoundencompass a reaction product that is obtained by a reaction of (i) adialkylaminoalkylamine compound, (ii) a cyclic amine compound which hasone or more nitrogen atoms bonded with active hydrogen in a molecule,and (iii) a diisocyanate compound.

Alternatively, the denatured aliphatic polyamine compound can be areaction product obtained by reacting, as a fourth component, (iv) anepoxy compound with the above three components (i), (ii), and (iii).

Among the denatured aliphatic polyamine compounds, it is possible tosuitably use a reaction product which is obtained by a thermal reactionof three components, i.e., the above (i), a cyclic amine compound whichhas one or two nitrogen atoms bonded with active hydrogen in a moleculeamong the above (ii), and the above (iii); or a reaction product whichis obtained by a thermal reaction of four components, i.e., the above(i), a cyclic amine compound which has one or two nitrogen atoms bondedwith active hydrogen in a molecule among the above (ii), the above(iii), and an epoxy compound having more than one epoxy group in amolecule on average among the above (iv).

Further, the denatured aliphatic polyamine compound can be compoundsdisclosed in Japanese Examined Patent Application Publication TokukoshoNo. 58-55970 (1983), Japanese Patent Application Publication TokukaishoNo. 59-27914 (1984), Japanese Patent Application Publication TokukaishoNo. 59-59720 (1984), Japanese Patent Application Publication TokukaiheiNo. 3-296525 (1991), and the like.

Here, the above (i) dialkylaminoalkylamine compound is not limited to aparticular one, and it is possible to suitably use, for example, acompound having a structure represented by Formula (1) below.

where R independently represents a straight-chain or branched-chainC1-C4 alkyl group, and n represents 2 or 3.

Concrete examples of the (i) dialkylaminoalkylamine compound encompassdimethylaminopropylamine, diethylaminopropylamine,dipropylaminopropylamine, dibutylaminopropylamine,dimethylaminoethylamine, diethylaminoethylamine, dibutylaminoethylamine,and the like. Among these, the (i) dialkylaminoalkylamine compound isparticularly preferably dimethylaminepropylamine ordiethylaminopropylamine. The (i) dialkylaminoalkylamine compounds can beused alone or in combination of two or more. In a case where the (i)dialkylaminoalkylamine compounds are used in combination, ratios of the(i) dialkylaminoalkylamine compounds can be arbitrarily determined.

The (ii) cyclic amine compound which has one or more nitrogen atomsbonded with active hydrogen in a molecule is not limited to a particularone. Specifically, examples of the above (ii) encompass polyamines andmonoamines such as metaxylylenediamine, 1,3-bis(aminomethyl)cyclohexane,isophoronediamine, diaminecyclohexane, phenylenediamine,toluylenediamine, diaminodiphenylmethane, diaminodiphenyl sulfone,piperazine, N-aminoethylpiperazine, benzylamine, and cyclohexylamine.

Among these, the cyclic amine compound is particularly preferablymetaxylylenediamine, 1,3-bis(aminomethyl)cyclohexane, isophoronediamine,N-aminoethylpiperazine, cyclohexylamine, or benzylamine.

Among these amine components, polyamines have, as a curing agentcompound, a function as a molecular chain growth material, andmonoamines have a function as a molecular weight adjusting material. The(ii) cyclic amine compounds which have one or more nitrogen atoms bondedwith active hydrogen in a molecule can be used alone or in combinationof two or more. In a case where the (ii) cyclic amine compounds are usedin combination, ratios of the (ii) cyclic amine compounds can bearbitrarily determined.

The (iii) diisocyanate is not limited to a particular one. Specifically,examples of the (iii) diisocyanate encompass isophoronediisocyanate,metaxylylenediisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane,2,4-toluylenediisocyanate, 2,6-toluylenediisocyanate,1,5-naphthylenediisocyanate, 1,4-phenylenediisocyanate,diphenylmethane-4,4′-diisocyanate,2,2′-dimethyldiphenylmethane-4,4′-diisocyanate,hexamethylenediisocyanate, trimethylhexamethylenediisocyanate, and thelike.

Among these, the (iii) diisocyanate is particularly preferablydiisocyanate having a cyclic structure. The (iii) diisocyanates can beused alone or in combination of two or more. In a case where the (iii)diisocyanates are used in combination, ratios of the (iii) diisocyanatescan be arbitrarily determined.

The (iv) epoxy compound is not limited to a particular one.Specifically, examples of the (iv) epoxy compound encompass glycidylethers obtained by reacting epichlorohydrin with polyhydric phenol suchas bisphenol A, bisphenol F, bisphenol S, hexahydrobisphenol A,tetramethylbisphenol A, catechol, resorcin, cresol novolac,tetrabromobisphenol A, trihydroxybiphenyl, bisresorcinol,bisphenolhexafluoroacetone, hydroquinone, tetramethylbisphenol A,tetramethylbisphenol F, triphenylmethane, tetraphenylethane, andbixylenol; polyglycidyl ethers obtained by reacting epichlorohydrin andaliphatic polyhydric alcohol such as glycerin, neopentyl glycol,ethylene glycol, propylene glycol, butylene glycol, hexylene glycol,polyethylene glycol, and polypropylene glycol; glycidyl ether estersobtained by reacting epichlorohydrin with hydroxycarboxylic acid such asp-hydroxy benzoic acid and β-oxynaphthoic acid; polyglycidyl estersobtained from polycarboxylic acids such as phthalic acid, methylphthalicacid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid,hexahydrophthalic acid, endo methylenehexahydrophthalic acid,trimellitic acid, and polymerized aliphatic acid; glycidylaminoglycidylethers obtained from aminophenol, aminoalkylphenol, and the like;glycidylaminoglycidyl ester obtained from aminobenzoic acid;glycidylamines obtained from aniline, toluidine, tribromaniline,xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfone, and the like;epoxidized polyolefin; glycidylhydantoin; glycidylalkylhydantoin;triglycidyl cyanurate; and monoepoxides such as butyl glycidyl ether,phenyl glycidyl ether, alkylphenyl glycidyl ether, benzoic acid glycidylester, and styrene oxide.

The (iv) epoxy compounds can be used alone or in combination of two ormore. In a case where the (iv) epoxy compounds are used in combination,ratios of the (iv) epoxy compounds can be arbitrarily determined.

It is more preferable that the (iv) epoxy compound is a combination ofpolyepoxide having a plurality of epoxy groups in a molecule andmonoepoxide having one (1) epoxy group in a molecule.

As the polyepoxide, it is particularly preferable to use, for example,diepoxide such as bisphenol A type diepoxide whose epoxy equivalent isapproximately 190, bisphenol F type diepoxide whose epoxy equivalent isapproximately 175, diglycidyl aniline, or diglycidylorthotoluidine.

As the monoepoxide, it is particularly preferable to use phenyl glycidylether, methylphenyl glycidyl ether, butylphenyl glycidyl ether, or thelike.

Among these epoxides, polyepoxide, particularly diepoxide has a functionas a molecular chain growth material, and monoepoxide has a function asa molecular weight adjusting material.

As the denatured aliphatic polyamine compound, it is possible tosuitably use a commercially available general denatured aliphaticpolyamine compound. Such a commercially available product is not limitedto a particular one and can be, for example, FUJICURE (RegisteredTrademark) FXE-1000, FXR-1030, FXB-1050 (manufactured by Fuji Kasei Co.,Ltd.), or the like.

(7-2. Imidazole Compound)

The imidazole compound serving as a curing assistant agent is preferablyan epoxy resin imidazole adduct compound. The epoxy resin imidazoleadduct compound is basically a reaction product (in general, which iscalled “epoxy compound imidazole adduct”) obtained by a reaction of anepoxy compound and an imidazole compound. Specifically, the epoxy resinimidazole adduct compound (i.e., epoxy compound imidazole adduct) is areaction product obtained from an imidazole compound which (i) has, in amolecule, one or more active hydrogens that can cause addition reactionwith epoxy groups of monofunctional and polyfunctional epoxy compoundsand (ii) has one or more imidazole groups in at least one molecule.

The imidazole compound is preferably one or more compounds selected fromthe group consisting of 1-cyanoethyl-2-methylimidazole,1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole,1-cyanoethyl-2-phenylimidazole,1-cyanoethyl-2-undecylimidazoliumtrimellitate,1-cyanoethyl-2-phenylimidazoliumtrimellitate,2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine,2-phenylimidazole isocyanuric acid addition product, 2-methylimidazole,2-undecylimidazole, 2-ethyl-4-methylimidazole,2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole,1-benzyl-2-phenylimidazole, and 1,2-dimethylimidazole.

As the epoxy compound, it is possible to use bisphenol A diglycidylether, bisphenol F diglycidyl ether, or the like.

Such a reaction product obtained by reaction of an epoxy compound withan imidazole compound encompasses reaction products obtained by areaction of an imidazole compound with any of aliphatic, alicyclic,aromatic, and heterocyclic epoxy compounds. Therefore, a chemicalstructure of the epoxy compound imidazole adduct is not definitelydetermined and can be exemplified by those disclosed in Japanese PatentApplication Publication Tokukaisho No. 62-285913 (1987), Japanese PatentApplication Publication Tokukaihei No. 3-139517 (1991), Japanese PatentApplication Publication Tokukaihei No. 6-49176 (1994), Japanese PatentApplication Publication Tokukaihei No. 6-211969 (1994), Japanese PatentApplication Publication Tokukaihei No. 7-196776 (1995), and the like.

A commercially available product of the epoxy resin imidazole adductcompound is not limited to a particular one, and it is possible to useAJICURE (Registered Trademark) PN-23, PN-R (which are manufactured byAjinomoto Fine-Techno Co., Inc.), or the like. The epoxy resin imidazoleadduct compounds can be used alone or in combination of two or more. Ina case where the epoxy resin imidazole adduct compounds are used incombination, ratios of the epoxy resin imidazole adduct compounds can bearbitrarily determined.

(7-3. Thiol Compound)

As the thiol compound serving as a curing assistant agent, it ispossible to suitably use any of the above exemplified thiol compoundswhich can be contained in the above described encapsulated curing agent.

(7-4. Acid Anhydride Compound)

Examples of the acid anhydride curing agent encompass phthalicanhydride, trimellitic anhydride, pyromellitic anhydride,hexahydrophthalic anhydride, tetrahydrophthalic anhydride,3-chlorophthalic anhydride, 4-chlorophthalic anhydride,benzophenonetetracarboxylic anhydride, succinic anhydride,methylsuccinic anhydride, dimethylsuccinic anhydride, dichlorosuccinicanhydride, methylnadic acid, dodecylsuccinic acid, maleic anhydride, andthe like. These compounds can be used alone or in combination of two ormore. In a case where the compounds are used in combination, ratios ofthe compounds can be arbitrarily determined.

(7-5. Thermal Acid Generating Agent)

Examples of the thermal acid generating agent encompass triarylsulfoniumsalt, monosulfonium salt, bissulfonium salt, iodonium salt, a phenacylcompound, and the like.

(8. Irradiation with Laser Light)

The resin composition in accordance with the present invention can becured by a step (a) of directly and/or indirectly irradiating the resincomposition with an energy beam. Here, a case of irradiating with laserlight will be described.

From the viewpoint of carrying out sufficient curing in a short time,the laser light has a wavelength whose lower limit is preferably 600 nmor more, 800 nm or more, 900 nm or more, and particularly preferably 800nm or more or 900 nm or more. Moreover, from a similar viewpoint, anupper limit of the wavelength is preferably 1500 nm or less, and morepreferably 1000 nm or less.

A type of a laser is not limited to a particular one, provided that thelaser light having the above wavelength can be emitted. For example, thetype of the laser can be an He—Ne laser, a semiconductor laser, a CO₂laser, an Nd:YAG laser, or the like.

By directly and/or indirectly irradiating the resin composition inaccordance with the present invention with laser light, it is possibleto sufficiently cure the resin composition in a very short time, i.e.,in several seconds. An irradiation time with laser light is preferably 5seconds or more, preferably 7 seconds or more, and more preferably 10seconds or more.

In Examples described later, it was confirmed that an inside of theresin composition in accordance with the present invention wassufficiently cured by irradiation with laser light for 10 seconds. Note,however, that the irradiation time is not limited to 10 seconds.

The resin composition in accordance with the present invention can besufficiently cured in an irradiation time of several seconds, andtherefore a long irradiation time is not necessary. Further, irradiationfor an excessively long time may heat up peripheral components and thismay lead to shape deformation, and therefore an upper limit of theirradiation time with laser light is preferably 20 seconds or less, morepreferably 15 seconds or less, and particularly preferably 10 seconds orless.

The description “directly irradiating the resin composition with laserlight” means that the resin composition is irradiated with laser lightvia no other members. Meanwhile, the description “indirectly irradiatingthe resin composition with laser light” means that, for example, theresin composition is irradiated with laser light which has passedthrough another member.

For example, in a case where the resin composition in accordance withthe present invention is applied to any of or both of two surfaces ofrespective adherends which are to be bonded together and consequentlythe resin composition is sandwiched between the two surfaces, the resincomposition is to be irradiated with laser light which has passedthrough the adherend. In this case, the resin composition is indirectlyirradiated with laser light.

Meanwhile, the case where the resin composition in accordance with thepresent invention is directly irradiated with laser light can be a casewhere, for example, the resin composition which has been applied to asurface of a certain member is directly irradiated with laser light.

In this case, although bonding of members is not intended, the presentinvention has found for the first time that a firm cured product can beobtained in an extremely short time by irradiating the resin compositionin accordance with the present invention with laser light, withoutplacing an excessive heat load on a part that is around a part to whichthe resin composition has been applied. This finding can be consideredas significantly useful. Therefore, an aspect in which the resincomposition is directly irradiated with laser light also falls withinthe scope of the present invention.

The resin composition in accordance with the present invention containsan encapsulated curing agent. In a case where the resin composition isirradiated with laser light, the shell is cleaved by the heat energy,and the curing agent contained in the core cures the epoxy resincontained in the resin composition. Conventionally, an encapsulatedcuring agent has been used in order to gradually proceed with a curingreaction by gradually melting a shell with heat.

In the present invention, the resin composition in accordance with thepresent invention is irradiated with laser light at a timing at which acuring reaction is intended to occur. From this, the shell is cleaved atone stroke, and thus a curing reaction is quickly carried out. As aresult, it has been found that an epoxy resin can be cured in a veryshort time and a cured product having high durability can be obtained,unlike a conventional method in which a one-part epoxy resin compositionis cured with heat.

The encapsulated curing agent stably exists in the resin composition inaccordance with the present invention in a normal state, and thereforethe resin composition is long in work life and is excellent inworkability. Moreover, the encapsulated curing agent includes the corewhich contains a curing agent inside the shell, and thus the curingagent is in an encapsulated state. Energy of laser light is concentratedon the shell, and it is therefore possible to quickly cure the bisphenolA epoxy resin that exists in the vicinity of the encapsulated curingagent after the shell is cleaved. The bisphenol A epoxy resin generatesheat when being cured, and the heat propagates in the resin composition.As a result, curing of the whole epoxy resin contained in the resincomposition is also finished in a very short time.

On the other hand, a general one-part epoxy resin composition which ismixed with a bisphenol A epoxy resin is to be dispersed in the bisphenolA epoxy resin, and therefore energy of laser light is not necessarilyconcentrated on the one-part epoxy resin composition. Therefore, asindicated in Comparative Example described later, sufficient curing doesnot seem to be carried out even by irradiating, with laser light, aconventional one-part epoxy resin composition which does not contain anencapsulated curing agent.

In the encapsulated curing agent, the core and the shell are in a formof liquid, and a pseudo interface is formed between the core and theshell. The interface easily disappears when the encapsulated curingagent is irradiated with laser light, and it is therefore possible toquickly cure the bisphenol A epoxy resin.

On the other hand, a general one-part epoxy resin composition is in aform of powder, and therefore a curing reaction starts after a solid ischanged into a liquid. That is, in addition to energy necessary for thecuring reaction, energy for changing the solid into the liquid isrequired. This also seems to be a reason that sufficient curing cannotbe carried out even by irradiating the general one-part epoxy resincomposition with laser light.

As such, it is possible to concentratively apply energy of laser lightto the curing agent contained in the encapsulated curing agent. Fromthis, for example, in a case where the resin composition in accordancewith the present invention is applied to a plurality of parts in anelectronic component, it is possible to bond the plurality of parts byirradiating each of the parts with laser light, without applying heat tothe whole electronic component.

It is possible to carry out curing in a plurality of parts at one timeby simultaneously irradiating the plurality of parts with respective ofa plurality of rays of branched laser light. The branching can be easilycarried out by, for example, using a laser light irradiation devicewhich can branch laser light with use of optical fibers.

Further, it is possible to sequentially carry out curing under differentconditions by using a plurality of laser light irradiation devices andsetting different irradiation conditions to the respective plurality oflaser light irradiation devices.

Embodiment 2

A method for curing the resin composition in accordance with the presentinvention can include a step (b) of directly or indirectly applyingenergy to the resin composition after the step (a), the energy beingdifferent from that of the laser light.

As described in Embodiment 1, the resin composition in accordance withthe present invention can be sufficiently cured in a short time only bythe step (a). Here, for example, even in a case where an area of a partto which the resin composition in accordance with the present inventionis applied is large (e.g., an area of approximately 5 cm×5 cm), theeffect can be brought about by scanning the whole area with laser light.

Meanwhile, the laser light is to be locally applied. From this, in acase where a large area needs to be irradiated and a curing reaction bythe laser light irradiation is assisted by directly or indirectlyapplying energy different from that of the laser light (i.e., heatenergy of laser light) to the resin composition in accordance with thepresent invention, it is possible to more efficiently carry out thecuring reaction. Moreover, the application of other energy is effectivenot only in the case where a large area needs to be irradiated withlaser light but also in a case where more complete curing is intended tobe carried out. In view of the above, the embodiment including the step(b) also falls within the present invention.

Examples of the energy different from that of laser light encompassenergy beams such as an ultraviolet ray, an electron beam, an infraredray, an X-ray, a sun beam, and heat rays such as emanation andradiation; heat energy by conduction obtained from energy sources suchas a heater; and the like.

In a case where the resin composition in accordance with the presentinvention is subjected to the step (b) after the step (a), theapplication of other energy is assistive because curing by the step (a)is already proceeding. From this, even in a case where the step (b) isadditionally carried out, an adverse effect such as deformation of amember caused by an excessive heat load hardly occurs.

With regard to the meaning of the description “directly or indirectly”,the description in Embodiment 1 applies. A time for applying the otherenergy is preferably 30 seconds or more and 5 minutes or less, becausethe application of other energy is carried out in order to facilitate asubsidiary curing reaction.

Embodiment 3

In a resin composition curing method in accordance with Embodiment 3,the resin composition in accordance with the present invention issandwiched between a surface of at least one adherend and a surface ofanother adherend which is different from the at least one adherend. Themethod includes a step (a) of directly and/or indirectly irradiating theresin composition in accordance with the present invention with laserlight. As a result, the resin composition in accordance with the presentinvention is cured, and thus the at least one adherend and the anotheradherend are bonded together. In this specification, the term “adherend”indicates a subject to be bonded.

The description “the resin composition in accordance with the presentinvention is sandwiched between a surface of at least one adherend and asurface of another adherend which is different from the at least oneadherend” means that the resin composition in accordance with thepresent invention exists between the surface of the at least oneadherend and the surface of the another adherend different from the atleast one adherend.

Examples of such a case encompass a case where the resin composition inaccordance with the present invention is applied to a surface of atleast one adherend, and a surface of another adherend which is differentfrom the at least one adherend is attached to the surface on which theresin composition has been applied, so that the resin composition existsbetween the surfaces. A method for carrying out the bonding is notlimited to a particular one, and can be carried out by (i) stacking thesurface of the another adherend onto the resin composition which hasbeen applied to the surface of the at least one adherend and (ii)applying appropriate pressure thereto.

FIG. 1 is a view schematically illustrating a state in which (i) a resincomposition 1 in accordance with the present invention is applied to asurface of an adherend 2, (ii) a surface of another adherend 3 isattached onto the resin composition 1, and (iii) an upper surface of theanother adherend 3 is irradiated with laser light. The arrows in FIG. 1indicate the laser light.

The laser light passes through the adherend 3 and then reaches the resincomposition 1 in accordance with the present invention. Thus, a curingreaction is ended in a short time, and the adherend 2 and the anotheradherend 3 are firmly bonded together.

In FIG. 1, the laser light is emitted toward the upper surface of theanother adherend 3. Note, however, that an aspect of the laser lightirradiation is not limited to this. For example, laser light can beemitted from a lower surface side of the adherend 2 in FIG. 1, or can beemitted from both the upper surface side and the lower surface side, orcan be emitted toward one or more four lateral surfaces of the resincomposition 1 in accordance with the present invention in FIG. 1.

With regard to the “surface of the at least one adherend”, the “surface”can be one surface or can be two or more surfaces. For example, in acase where the at least one adherend is a plate member, the surface canbe a front surface and/or a rear surface of each of the at least oneadherend. That is, it is possible that (i) the resin composition inaccordance with the present invention is applied only to a front surfaceor a rear surface of the plate member and a surface of the anotheradherend is attached to the front surface or the rear surface or (ii)the resin composition in accordance with the present invention isapplied to the front surface and the rear surface of the plate memberand surfaces of other adherends are attached to respective of the frontsurface and the rear surface.

Of course, the adherend is not limited to the plate member, providedthat the adherend has a surface.

In each of one or more surfaces of the at least one adherend, the resincomposition in accordance with the present invention can be applied inone part or can be applied in a plurality of parts.

The resin composition in accordance with the present invention can beapplied to the “another adherend”. Alternatively, in a case where theresin composition in accordance with the present invention is applied tothe “at least one adherend” to which the another adherend is to beattached, the resin composition in accordance with the present inventiondoes not need to be applied to the “another adherend”.

The number of the “another adherend” which is to be attached to onesurface of the “at least one adherend” can be one or can be two or more.

A material of the adherend is not limited to a particular one. Moreover,materials of the “at least one adherend” and the “another adherend” canbe identical materials or can be different materials. As the material,for example, a general resin can be used. Examples of the resinencompass super engineering plastics such as polysulfone,polyethersulfone, polyallylate, polyamideimide, polyetherimide, liquidcrystal polymer, polytetrafluoroethylene, polychlorotrifluoroethylene,and polyvinylidene fluoride; engineering plastics such as 6-nylon,66-nylon, polyacetal, polycarbonate, polyethylene terephthalate,modified polyphenyleneether, and polybutylene terephthalate; commodityplastics such as polyvinyl chloride, polyethylene, polypropylene,polystyrene, ABS, and polymethyl methacrylate; thermoplastics such asphenol resin, urea resin, melamine resin, epoxy resin, unsaturatedpolyester, silicon resin, and polyurethane; and the like. The resin canbe a resin composition which further contains another component such asa surface treatment agent.

One of the adherends for sandwiching the resin composition in accordancewith the present invention can be a heat conductive member whichcontains metal. Examples of a material of the heat conductive memberencompass metals themselves such as aluminum, an aluminum alloy, copper,a copper alloy, iron, an iron alloy, nickel, tin, lead, gold, silver,and silicon; and a thermal conductor in which metal is contained in theresin or the resin composition with a high concentration in order togive electrical conductivity or the like.

The high concentration means that the resin or the resin compositioncontains metal as a main component. The description “contains metal as amain component” means to contain metal not less than 50% by weightrelative to 100% by weight (i.e., total weight) of the resin or theresin composition and the metal.

Embodiment 4

In a resin composition curing method in accordance with Embodiment 4,the at least one adherend is a heat conductive member that containsmetal, and the method includes a step (c) of heating at least the heatconductive member, a step (d) of applying the resin composition inaccordance with the present invention to the surface of the heatconductive member which has been subjected to the step (c) and/orapplying the resin composition to the surface of the another adherend,and a step (e) of attaching the surface of the heat conductive member,which has been subjected to the step (d), to the surface of the anotheradherend, and the steps (c), (d), and (e) are carried out before thestep (a) so that the resin composition is sandwiched between the surfaceof the at least one adherend and the surface of the another adherend.

With regard to the heat conductive member containing metal, thedescription in Embodiment 3 applies. Moreover, as a material of theanother adherend, it is possible to preferably use, for example, any ofthe resins and the resin compositions containing the resins which aredescribed in Embodiment 3.

In the step (c), at least the heat conductive member is heated. In acase where bonding is carried out with use of (i) the heat conductivemember containing metal as an adherend and (ii) the resin composition inaccordance with the present invention as in Embodiment 4, it is possiblethat the bisphenol A epoxy resin contained in the resin composition iscured by carrying out the step (a), and consequently the resincomposition is cured, and thus the bonding is carried out.

However, in a case where the adherend contains metal, heat given bylaser light is more likely to be conducted through the metal. From this,a part of heat (energy) given by irradiation with laser light is notused in a curing reaction, and the curing reaction tends to be slowerthan a case where the adherend does not contain metal.

In Embodiment 4, the heat conductive member is heated in advance in thestep (c), and therefore the heat conductive member is in a state ofbeing given heat energy before irradiation with laser light. This makesit possible to prevent heat given by the laser light from beingconducted through the heat conductive member, and it is thereforepossible to use most of the heat (energy) given by the laser light forthe curing reaction.

The heating can be carried out by, for example, placing the heatconductive member in a constant temperature bath and applying heatenergy to the heat conductive member, or the like. The heating ispreferably carried out for 30 seconds to 5 minutes while keeping atemperature of an atmosphere in the constant temperature bath at 80° C.to 120° C.

In a case where the another adherend does not contain metal, it is notparticularly necessary to heat up the another adherend. However, theheating can be carried out to an extent that an excessive heat load isnot exerted.

As above described, it is possible to preferably use, as a material ofthe another adherend, any of the resins and the resin compositionscontaining the resins which are described in Embodiment 3. It ispreferable that the another adherend does not contain metal but theanother adherend can contain metal in an amount in which the metal doesnot become a main component in the another adherend.

That is, the another adherend may contain less than 50% by weight ofmetal, relative to 100% by weight (i.e., total weight) of the resindescribed in Embodiment 3 or the resin composition containing the resin,and the metal. In a case where the another adherend contains metal in anamount in which the metal does not become a main component in theanother adherend, it is preferable that the another adherend is alsosubjected to the step (c).

In the step (d), the resin composition in accordance with the presentinvention is applied to the surface(s) of the heat conductive memberand/or the another adherend which have/has been subjected to the step(c). Next, in the step (e), the surface of the heat conductive memberwhich has been subjected to the step (d) is bonded to the surface of theanother adherend. Aspects of application and bonding are identical withthose described in Embodiment 3. The steps (c) through (e) are carriedout before the step (a), and therefore the resin composition inaccordance with the present invention is directly and/or indirectlyirradiated with laser light after the bonding.

As such, according to Embodiment 4, it is possible to efficiently carryout the curing reaction even in a case where metal and a resin arebonded to each other. As a result, it is possible to firmly bond themetal and the resin together.

Embodiment 5

In a resin composition curing method in accordance with Embodiment 5,the sandwiching is carried out by applying the resin composition inaccordance with the present invention between the surface of the atleast one adherend and the surface of the another adherend in a part inwhich at least part of the another adherend is inserted in the surfaceof the at least one adherend. In Embodiment 5, it is preferable that theat least one adherend is a resin molded product and the another adherendis a terminal. The terminal can be a conventionally known metalterminal.

FIG. 2 is a view schematically illustrating a state in which a terminal4 is bonded to the adherend 2 which is a resin molded product and theterminal 4 is sealed with use of the resin composition 1 in accordancewith the present invention by the method in accordance with Embodiment5. The resin molded product is a product which has been obtained bymolding a resin or a resin composition to have an intended shape by aconventionally known molding method such as injection molding.

The “part in which at least part of the another adherend is inserted inthe surface of the at least one adherend” (hereinafter, referred to as“inserted part”) indicates a part including (i) a recessed part that isformed in the surface of the at least one adherend and corresponds to adiameter of the another adherend and (ii) the at least part of theanother adherend which part is inserted in the recessed part.

FIG. 3 is a vertical cross-sectional view illustrating the adherend 2illustrated in FIG. 2 to which the terminal 4 is bonded and sealed. InFIG. 3, the recessed part is indicated by the reference numeral 2′, andthe inserted part is indicated by oblique lines in the recessed part 2′and the terminal 4.

In this case, in the inserted part, a bottom surface and a lateralsurface of the recessed part 2′ in the surface of the adherend 2corresponds to the “surface of the at least one adherend”, and the partof the terminal 4 which part is indicated by the oblique linescorresponds to the “surface of the another adherend”.

As illustrated in FIG. 3, the resin composition 1 in accordance with thepresent invention is applied between the surface of the at least oneadherend and the surface of the another adherend, and thus the recessedpart 2′ is filled with the resin composition 1 in accordance with thepresent invention. As such, the resin composition 1 in accordance withthe present invention is sandwiched between the surface of the at leastone adherend and the another adherend.

Further, the resin composition 1 in accordance with the presentinvention is irradiated with laser light in the step (a) so that theresin composition 1 in accordance with the present invention is cured,and thus the terminal 4 can be bonded to the adherend 2 and can besealed. In this case, the terminal 4 conducts heat given by the laserlight, and this makes it possible to completely cure the sandwichedresin composition 1 in accordance with the present invention.

A method for carrying out the application of the resin composition inaccordance with the present invention is not limited to a particularone, and the resin composition in accordance with the present inventioncan be supplied to the recessed part 2′ with a conventionally knownmethod.

In Embodiment 5, it is possible to bond and seal even an adherend, whichhas a small diameter like a terminal, to the other adherend firmly andwithout positional displacement. Further, the resin composition inaccordance with the present invention can be cured in a short time andtherefore, even in a case where the resin molded product to which theterminal is bonded is low in resistance to high temperature, deformationof the resin molded product does not occur. Therefore, the resincomposition in accordance with the present invention can be extremelysuitably used in production of electronic components such as a relay anda switch.

In FIGS. 2 and 3, the case is described in which one adherend is bondedto another adherend and sealed. Note, however, that the presentinvention is of course not limited to this. For example, a personskilled in the art can sufficiently understand that (i) it is possiblethat a plurality of terminals are bonded to and sealed in one surface ofone resin molded product or (ii) it is possible that a plurality ofterminals are bonded to and sealed in respective of a plurality ofsurfaces of a plurality of resin molded products.

Embodiment 6

In Embodiments 1 through 5, the cases are mainly described in which theresin composition is irradiated with laser light. Note, however, thatthe present invention is not limited to those. The resin composition inaccordance with the present invention can be cured with another energydifferent from that of laser light.

In a case where the another energy is applied to the resin compositionin accordance with the present invention, the color material assistsheat absorption by the resin composition, and therefore curing can becarried out in a shorter time and a heat load on a part around a part inwhich the resin composition has been applied can be reduced, as comparedwith a case where a conventional one-part epoxy resin is used.

Further, by appropriately selecting a color material to be used fromcarbon black and a pigment and/or a dye different from carbon blackbased on a film thickness of a film obtained by applying the resincomposition, it is possible to more efficiently carry out curing in acase where the another energy is applied.

Examples of the another energy different from that of laser lightencompass energy described as “another energy” in Embodiment 2: e.g.,energy beams such as an ultraviolet ray, an electron beam, an infraredray, an X-ray, a sun beam, and heat rays such as emanation andradiation; heat energy by conduction obtained from an energy source suchas a heater; and the like.

As the another energy, it is preferable to use an infrared ray becausethe infrared ray can be used for general purposes and an effect offacilitating a reaction due to heat absorption by a material can beexpected. A wavelength of the infrared ray is preferably 500 nm or moreand 1000 nm or less, and further preferably 600 nm or more and 800 nm orless, in view of carrying out sufficient curing in a short time.

As a method of irradiation with an infrared ray, it is possible toemploy a conventionally known method. For example, it is possible toemploy a method in which a polybutylene terephthalate (PBT) plate or thelike on which the resin composition in accordance with the presentinvention has been applied is placed in a conventionally known infraredcuring oven, and the resin composition is directly and/or indirectlyirradiated with an infrared ray for two minutes or more and one hour orless so that a temperature of an atmosphere in the oven becomes 80° C.or higher and 200° C. or lower.

In a case where an infrared ray is used as the another energy and thefilm obtained by applying the resin composition in accordance with thepresent invention has a film thickness of less than 300 μm, as earlydescribed, the resin composition in accordance with the presentinvention contains carbon black by preferably not less than 0.01 partsby weight and not more than 20 parts by weight, more preferably not lessthan 0.5 parts by weight and not more than 10 parts by weight, andparticularly preferably not less than 1 part by weight and not more than7 parts by weight, relative to 100 parts by weight of the bisphenol Aepoxy resin. In this case, it is possible to efficiently carry outcuring in an extremely short time, and it is possible to obtain a curedproduct whose durability is high.

Embodiment 7

In Embodiment 7, a cured product of the resin composition in accordancewith the present invention will be described. A cured product which isobtained by, as above described, curing the resin composition inaccordance with the present invention by applying energy of laser lightincludes two or more layers, and an outermost surface layer among thetwo or more layers contains a cured product of the bisphenol A epoxyresin as a main component.

The inventors of the present invention have found the followings: thatis, in a case where the resin composition in accordance with the presentinvention is irradiated with laser light and is thus cured, a relativelythick layer is formed in an outermost surface layer when a verticalcross section of the cured product is observed, and the layer contains acured product of the bisphenol A epoxy resin as a main component, unlikea case where a general one-part epoxy resin is cured.

The “two or more layers” indicate a laminated structure that is seenwhen the vertical cross section of the cured product is observed with amicroscope (in a magnification of preferably 50 times or more and 500times or less), and mean that the laminated structure is configured byat least two layers.

The “outermost surface layer” indicates an outermost layer among the twoor more layers. For example, in a case where the resin composition isapplied to an adherend and is cured, the outermost surface layer is alayer which is positioned on a farthest side from the adherend. Notethat the vertical cross section of the cured product can be prepared bya method such as cross section polishing in which a cross section of thecured product is polished so that a cross-sectional structure can beseen.

The description “the outermost surface layer contains a cured product ofthe bisphenol A epoxy resin as a main component” means that a weight ofthe cured product of the bisphenol A epoxy resin accounts for more than50% by weight relative to 100% by weight of components contained in theoutermost surface layer.

A weight ratio of the cured product of the bisphenol A epoxy resinrelative to the components contained in the outermost surface layer ispreferably as high as possible, and is preferably more than 60% byweight, more than 70% by weight, more than 80% by weight, more than 90%by weight, more than 95% by weight, in ascending order, and mostpreferably 100% by weight.

A method for confirming the ratio can be, for example, a method bycomposition analysis such as EDAX. Moreover, it is easy for a personskilled in the art to distinguish the cured product of the bisphenol Aepoxy resin, the filler, and the color material when the vertical crosssection is observed with the microscope. From this, in a case where thecured product of the bisphenol A epoxy resin evidently accounts for alarge part of the outermost surface layer in the vertical cross section,it is possible to confirm that the outermost surface layer contains thecured product of the bisphenol A epoxy resin as a main component,without obtaining the ratio.

For example, in a case where the resin composition in accordance withthe present invention is used as an adhesive agent, rigidity isessential for bonding with high quality. However, if external force isapplied to a cured product of the resin composition and the externalforce reaches an inner part of an adhesive layer (i.e., inside of thecured product) having high rigidity, a crack is more likely to occur inthe cured product, and the cured product is easily peeled off.

Moreover, an outermost surface layer of the adhesive agent is morelikely to receive external force. In a case where the outermost surfacelayer contains a cured product of a bisphenol A epoxy resin as a maincomponent, it can be expected that the outermost surface layer maymitigate the external force while maintaining rigidity of the adhesiveagent. Further, in that case where the outermost surface layer containsa cured product of a bisphenol A epoxy resin as a main component,improvements in humidity resistance and in insulating property can beexpected.

The present invention is not limited to the embodiments, but can bealtered by a skilled person in the art within the scope of the claims.An embodiment derived from a proper combination of technical means eachdisclosed in a different embodiment is also encompassed in the technicalscope of the present invention.

The present application includes the following invention:

The resin composition in accordance with the present invention containsa bisphenol A epoxy resin; an encapsulated curing agent including a corethat contains a curing agent and a shell that covers the core; a filler;and a color material.

According to the configuration, the encapsulated curing agent iscontained, and therefore the curing agent contained in the core of theencapsulated curing agent is stable in a state where no energy isapplied. Then, by directly and/or indirectly applying energy to theresin composition in accordance with the present invention, theencapsulated curing agent is cleaved by the energy and a curing reactionof the bisphenol A epoxy resin is started by the curing agent containedin the core.

It should be noted that the curing reaction is ended in an extremelyshort time, i.e., in several seconds, by irradiation with laser light aslater described in Examples. Moreover, for example, in a case wherecuring is carried out by irradiation with an infrared ray, it ispossible to finish the curing in a shorter time than a case where aconventionally known one-part epoxy resin composition is used.

Therefore, for example, in a case where the resin composition inaccordance with the present invention is used as an adhesive agent, itis possible to greatly efficiently carry out bonding or sealing betweenmembers, without exerting an excessive heat load to members of anelectronic component or the like.

It is therefore possible to prevent deformation of members due to heat,decrease in electrical characteristic of a metal part due to gas fromthe resin composition in accordance with the present invention does notoccur, and an electronic component or the like can be efficientlyproduced.

Moreover, according to the configuration, the curing time is extremelyshort, and this makes it possible to prevent the foregoing retention ofcomponents in the production process. This leads to reduction in size ofproduction facilities, and it is sufficiently possible to employinexpensive production facilities.

Further, the resin composition in accordance with the present inventionis a one-part composition and contains the encapsulated curing agent.From this, the resin composition is stable in quality and has a longwork life. Moreover, the resin composition contains the filler and istherefore excellent in rigidity and heat stability. Further, the resincomposition contains the color material and is therefore also high inheat absorbing efficiency. From this, according to the configuration, itis possible to stably and easily carry out the curing reaction.

As later described in Examples, a cured product obtained by theconfiguration has, as bonding quality, extremely high durability.

As above described, the present invention can solve the problems causedby the above described conventional one-part epoxy resin adhesive agent,two-part epoxy resin adhesive agent, UV-curable adhesive agent, instantadhesive agent, and the like. Thus, the present invention greatlycontributes to increase in efficiency of producing electronic componentsand in stability of quality.

It is preferable that the resin composition in accordance with thepresent invention contains the color material by not less than 1 part byweight and not more than 7 parts by weight, relative to 100 parts byweight of the bisphenol A epoxy resin; and the color material is carbonblack.

In a case where a thickness of a film obtained by applying the resincomposition is relatively small, carbon black can particularly suitablycause the resin composition to efficiently absorb heat. Further, in acase where a contained amount of the carbon black is the above describedparts by weight, it is particularly suitably possible to shorten acuring time. As a result, it is possible to greatly reduce a heat loadon members and to reduce a used amount of the curing agent.

In the resin composition in accordance with the present invention, it isalso preferable that the color material is a pigment different fromcarbon black.

In a case where a thickness of a film obtained by applying the resincomposition is relatively large, the pigment different from carbon blackcan particularly suitably cause the resin composition to efficientlyabsorb heat. Therefore, in a case where the thickness of the film isrelatively large, it is particularly suitably possible to shorten acuring time. As a result, it is possible to greatly reduce a heat loadon members and to reduce a used amount of the curing agent.

In the resin composition in accordance with the present invention, it ispreferable that the pigment different from carbon black is one or morecompounds selected from the group consisting of an iron oxide compound,a phthalocyanine compound, a chrome oxide compound, and a coppercompound.

A heat absorbing efficiency of the pigment different from carbon blackis lower than that of carbon black but, in a case where the pigmentdifferent from carbon black is used, it is possible to easily cure adeep part of the film obtained by applying the resin composition.Therefore, according to the configuration, it is possible to obtain thecured product which is excellent in balance between a curing property ofthe deep part of the film and a curing property of the surface of thefilm.

In the resin composition in accordance with the present invention, it ispreferable that the core contains one or more curing agents selectedfrom the group consisting of an amine compound, an imidazole compound,and a thiol compound.

The curing agent is a curing agent which is more likely to start acuring reaction of an epoxy resin carried out with laser light whichserves as an energy source. According to the configuration, the curingagent is contained in the core, and therefore the curing agent isnormally kept in a stable state. In a case where a curing reaction isintended to be started, the resin composition is directly and/orindirectly irradiated with laser light, and thus the reaction can bestarted at a low temperature and in a short time.

Moreover, in a case where curing is carried out with use of a generalcuring oven or the like, heat which has been efficiently absorbed by thecolor material such as carbon black easily destroys a pseudo interfacebetween the core and the shell of the encapsulated curing agent. It istherefore possible to efficiently proceed with a curing reaction by thecuring agent contained in the core.

As such, by using the resin composition having the above configuration,it is possible to more efficiently cure the resin composition.

It is preferable that the resin composition in accordance with thepresent invention further contains one or more curing assistant agentsselected from the group consisting of an amine compound, an imidazolecompound, a thiol compound, an acid anhydride compound, and a thermalacid generating agent.

According to the configuration, the curing assistant agent can furtherfacilitate a curing reaction by utilizing heat generated by the curingreaction caused by the curing agent contained in the encapsulated curingagent. Therefore, by using the curing assistant agent, it is possible toefficiently carry out a curing reaction in a shorter time.

In the resin composition in accordance with the present invention, it ispreferable that the filler is one or more fillers selected from thegroup consisting of fused silica, crystalline silica, and glass beads.

The filler is contained in order to improve rigidity and heat stabilityof the resin composition. Among those, fused silica, crystalline silica,and glass beads are fillers having high transparency. Therefore, in acase of being irradiated with laser light, it is possible to greatlyinhibit reflection of light, as compared with a normal white filler.From this, by using the filler, it is possible to not only improverigidity and heat stability of the resin composition but also proceedwith the curing reaction by laser light more efficiently.

The cured product of the resin composition in accordance with thepresent invention includes two or more layers, an outermost surfacelayer among the two or more layers containing a cured product of thebisphenol A epoxy resin as a main component.

According to the configuration, the main component of the cured productis the cured product of the bisphenol A epoxy resin. Therefore, even ina case where external force is applied to the outermost surface layer ofthe cured product, it is possible to mitigate the external force by theoutermost surface layer while the cured product has high rigidity.

As such, the cured product having the above features can inhibit theexternal force from reaching the inside of the cured product. Therefore,by using the cured product having the above features, it can be expectedthat a crack generated in the cured product and peeling off of the curedproduct can be inhibited. Moreover, it is possible to expectimprovements in humidity resistance and in insulating property of thecured product.

EXAMPLES

The following description will discuss further details of the presentinvention with reference to Examples. Note, however, that the presentinvention is not limited to the Examples.

Production Example

Adhesive agents A through K, α, and β were prepared by putting rawmaterials, which are for each of the adhesive agents A through K, α, andβ having respective compositions indicated in Table 1, into a container,then manually stirring the raw materials for three minutes with use of aglass rod, and then stirring the raw materials with use of a planetarycentrifugal mixer (manufactured by THINKY CORPORATION: Awatori RentaroARE-310) under conditions of 3-minute rotation and 3-minute revolution.The adhesive agents A through K fall under the above described resincomposition in accordance with the present invention. The adhesiveagents α and β are comparative adhesive agents used in ComparativeExamples. Note that a unit of values in Table 1 is parts by weight.

TABLE 1 Raw Materials A B C D E F G H I J K α β AER250 100 100 100 100100 100 100 100 100 100 100 100 100 (Bisphenol A epoxy resin)Dicyandiamide 20 AJICURE PN-23 5 5 5 5 5 5 5 5 5 5 (Epoxy resinimidazole adduct compound) NOVACURE HX-3722 20 20 20 20 20 20 20 20 2020 20 (Encapsulated curing agent) Silica 20 20 20 20 20 20 20 20 20 1010 10 10 Carbon black 3 5 7 10 1 1 1 1 1 Black iron oxide 10 15Phthalocyanine green 10 15 ADEKA OPTOMER CP77 2 (Thermal cationicpolymerization initiator)

In Table 1, AER (Registered Trademark) 250 (manufactured by Asahi KaseiE-Materials Corporation) was bisphenol A diglycidyl ether. Asdicyandiamide, OMICURE (Registered Trademark) DDA5 (manufactured by PTIJAPAN LTD.) was used. Dicyandiamide was used as a general curing agentwhich was a component of the comparative adhesive agent α.

AJICURE (Registered Trademark) PN-23 (manufactured by AjinomotoFine-Techno Co., Inc.) was an epoxy resin imidazole adduct compound andused as a curing assistant agent.

NOVACURE (Registered Trademark) HX-3722 (manufactured by Asahi KaseiE-Materials Corporation) was an encapsulated curing agent which is amixture of aromatic polyamine, a bisphenol A epoxy resin, and abisphenol F epoxy resin.

As silica, FB-5D (manufactured by DENKI KAGAKU KOGYO KABUSHIKI KAISHA)was used. The silica was fused silica. As carbon black which was aninorganic pigment, Mitsubishi carbon black MA7 (manufactured byMitsubishi Chemical Corporation) was used. As black iron oxide which wasan inorganic pigment, BL-100 (manufactured by DAITO KASEI KOGYO CO.,LTD.) was used. As phthalocyanine green, Chromo Fine (manufactured byDainichiseika Colour 86 Chemicals Mfg. Co., Ltd.) was used. ADEKAOPTOMER (Registered Trademark) CP77 (manufactured by ADEKA CORPORATION)was a thermal cationic polymerization initiator which starts curing byheat.

Example 1

The adhesive agents A through E prepared on respective polybutyleneterephthalate (PBT) plates having a thickness of 3 mm in ProductionExample were applied to respective plates each of which was made of PBT,and thus adhesive-agent-applied samples were prepared.

FIG. 4 is a view schematically illustrating a method for preparing anadhesive-agent-applied sample. First, 0.1 g of the adhesive agent A, B,C, D, or E (indicated by the reference numeral 1 in FIG. 4)corresponding to the resin composition in accordance with the presentinvention was dripped onto a PBT plate 2 (adherend) having a thicknessof 100 μm. Further, 200-μm thickness gauges (manufactured by MorimotoYasohachi Shoten Co., Ltd.) 5 were placed on both sides of the adhesiveagent A, B, C, D, or E, and then the adhesive agent A, B, C, D, or E wassqueegeed with a slide glass 6. Thus, samples were obtained in which theadhesive agents A, B, C, D, and E were respectively applied with athickness of 200 μm.

Next, the sample was placed in a small resin curing oven (UA-2,manufactured by TEIPI THERMAL ENGINEERING CO., LTD.) which was an IRoven, and heating was carried out for 6 minutes at an atmospheretemperature of 120° C. in the curing oven. Then, with use of FT-IR-ATR(PERKINELMER SYSTEM2000 FT-IR), one peak area of a glycidyl group at 910cm⁻¹ was compared between before and after curing, and thus a curingreaction rate was calculated. A relation between a peak area and acuring reaction rate was as follows:Curing reaction rate (%)=(absorbance peak area of glycidyl group aftercuring/absorbance peak area of methylene group after curing)/(absorbancepeak area of glycidyl group before curing/absorbance peak area ofmethylene group before curing)

With regard to absorbance areas of the glycidyl group and the methylenegroup, an absorbance peak area of the glycidyl group (in the vicinity ofabsorption site of 910 cm⁻¹) and an absorbance peak area of themethylene group (in the vicinity of absorption site of 2900 cm⁻¹) wereadopted. In general, a curing reaction rate of 80% or higher in theFT-IR is considered as being sufficiently cured. Results are shown inTable 2.

TABLE 2 Composition A B C D E Appearance No shine on No shine, No shine,No shine and Shine on surface, Completely Completely no tucks onsurface, Tucks seen on cured cured surface, Not completely surface Notcompletely cured cured inside Curing reaction 54% 91% 92% 70% 23% rate(%)

From the results shown in Table 2, it was found that the curing propertywas notably increased in a case where an amount of carbon black was 5parts by weight to 7 parts by weight, relative to 100 parts by weight ofthe bisphenol A epoxy resin.

That is, the followings were found: in a case where an infrared ray wasused as the irradiation energy and the amount of carbon black wasincreased, an infrared ray absorbing property was increased and a curingreaction was facilitated. Meanwhile, in a case where an amount of mixedcarbon black was a particular amount or more, it was difficult for heatto reach inside of the adhesive agent, and a difference in cured stateoccurred between the surface and the inside.

From the above results, it was found that, in a case where the filmthickness of the film obtained by applying the resin composition inaccordance with the present invention was relatively small (i.e., lessthan 300 μm) and an infrared ray was used as the irradiation energy, amost excellent amount of carbon black for curing was 5 parts by weightto 7 parts by weight, relative to 100 parts by weight of the bisphenol Aepoxy resin.

Example 2

The adhesive agent J prepared in Production Example was applied to a PBTplate, and thus an adhesive-agent-applied sample was prepared. With amethod identical with that described in Example 1, a sample of theadhesive agent J applied with a thickness of 200 μm was obtained.

Next, the sample of the adhesive agent J was irradiated, from above,with laser light having a diameter of 10 mm and an output of 6 W for 10seconds so that an area to be irradiated with the laser light becamelarger than an area in which the adhesive agent J was applied. In thatcase, a semiconductor laser apparatus (manufactured by Jenoptik JapanCo. Ltd., JOLD-30-FC-12 808) for emitting laser light having awavelength of 808 nm was used.

Subsequently, a cured state of a surface of the sample was confirmedwith use of a spatula, and it was confirmed that the surface wasentirely cured. Moreover, as with Example 1, a curing reaction rate wasevaluated by use of FT-IR-ATR, and it was confirmed that a curingreaction rate was 90% or higher.

In that case, an amount of deformation (amount of warpage) of the PBTplate was measured, and deformation was approximately 50 μm. As such, itwas possible to cure the adhesive agent in a short time without largelydeforming the member. The amount of deformation in curing was obtainedby the following method for measuring an amount of deformation.

That is, an amount of warpage of the PBT plate which warpage had beenincreased between before and after curing was measured, and thus theamount of deformation in curing was obtained. FIG. 5 is a viewschematically illustrating amounts of warpage of a PBT plate (adherend)before and after curing. In FIG. 5, the PBT plate (adherend) isindicated by the reference numeral 2.

As illustrated in FIG. 5, an amount of warpage of the PBT plate wasdefined as a difference between a maximum value and a minimum value ofheight positions obtained by scanning a cross section of the PBT plate.Further, the amount of deformation in curing is obtained by thefollowing formula.Amount of deformation in curing=amount of warpage (Xb) aftercuring−amount of warpage (Xa) before curing

The amount of warpage was measured with use of a surface roughness meter(SURFCOM, manufactured by Tokyo Seimitsu Co., Ltd.) under the followingconditions. The measurement was carried out three times, and an averagevalue was adopted:

-   T speed: 3.0 mm/s-   Cutoff value: 0.8 mm-   V-MAG: 100, H-MAG: 1-   TILT CORR, FLAT-ML-   Polarity: Positive

Example 3

A process similar to that of Example 2 was carried out, except that theadhesive agent K prepared in Production Example was used and the curingtime (i.e., laser light irradiation time) was changed from 10 seconds to7 seconds. A curing reaction rate was evaluated with use of theFT-IR-ATR, and it was confirmed that a curing reaction rate was 94%. Anamount of deformation (i.e., amount of warpage) of the PBT plate wasconfirmed, and deformation was approximately 50 μm. As such, theadhesive agent could be cured in a short time without greatly deformingthe member.

In Example 3, the imidazole compound was further added as an assistivecuring agent, and therefore more excellent curing could be carried outin a time shorter than that in Example 2.

The adhesive agent E of Example 1 was not completely cured by beingirradiated with an infrared ray. Moreover, in the adhesive agent A ofExample 1 also, tucks were seen on its surface. However, as shown inExamples 2 and 3, even in a case where a contained amount of carbonblack was 1 part by weight relative to 100 parts by weight of thebisphenol A epoxy resin as with the adhesive agent E, the excellentcuring reaction rate was obtained by being irradiated with laser light.

That is, the amount of carbon black contained in the resin compositionin accordance with the present invention is not limited to 5 parts byweight to 7 parts by weight relative to 100 parts by weight of thebisphenol A epoxy resin, and the resin composition in accordance withthe present invention can be sufficiently cured by selecting irradiationenergy even in a case where the amount of carbon black is less than 5parts by weight relative to 100 parts by weight of the bisphenol A epoxyresin.

Example 4

Onto a PBT plate having a thickness of 3 mm, 0.5 g of each of theadhesive agents F through I prepared in Production Example was dripped,and thus samples each of which had a thickness of 1 mm were obtainedwith the method described in Example 1.

Next, each of the samples was placed in the small resin curing oven(UA-2, manufactured by TEIPI THERMAL ENGINEERING CO., LTD.) and heatingwas carried out for 8 minutes at an atmosphere temperature of 120° C. inthe curing oven. Subsequently, an appearance was observed and a curingreaction rate was calculated, as with Example 1. Results are shown inTable 3.

TABLE 3 Composition F G H I Appearance No shine on No shine on No shineon No shine on surface, surface, surface, surface, No tucks No tucks Notucks No tucks Curing reaction 92% 91% 90% 92% rate (%)

Although black iron oxide and phthalocyanine green had an infrared rayabsorbing property lower than that of carbon black, from the resultsshown in Table 3, it was found that black iron oxide and phthalocyaninegreen had a good balance between infrared transmission into the insideof the sample and an infrared ray absorbing property. The followingswere also found: carbon black had an extremely high infrared rayabsorbing property, and therefore carbon black used in a film having athickness of Example 4 makes it difficult for an infrared ray to reachthe deep part. Meanwhile, black iron oxide and phthalocyanine green makeit easy for an infrared ray to reach the deep part even in a case whereblack iron oxide and phthalocyanine green are each used in such a film.

Example 5

Onto a PBT plate having a thickness of 3 mm, 0.1 g of each of theadhesive agents B, G, and I prepared in Production Example was dripped,and thus samples each of which had a thickness of 200 μm were obtainedwith the method described in Example 1.

Next, with use of the semiconductor laser apparatus used in Example 2,each of the samples was irradiated with IR laser light with a wavelengthof 808 nm, an output of 6 W, and a diameter of 10 mm, for 10 seconds.

Subsequently, an appearance was confirmed, and consequently it wasconfirmed that the surface and the inside were cured. By thus usinglaser light instead of the IR oven, it was possible to further shortenthe curing time.

Comparative Example 1

The comparative adhesive agent α prepared in Production Example wasapplied to a PBT plate as with the adhesive agent J, and thus a samplein which the comparative adhesive agent α was applied was prepared.

Next, the sample was placed in a small resin curing oven (UA-2,manufactured by TEIPI THERMAL ENGINEERING CO., LTD.), and curing wascarried out for 30 minutes at an atmosphere temperature of 120° C. inthe curing oven. As a result, a surface of the sample was confirmed, andthus entire curing was confirmed, as with Example 2.

A curing reaction rate was evaluated, and it was confirmed that thecuring reaction rate was 90% or higher.

However, in that case, an amount of deformation of the PBT plate was 500μm or more. That is, a heat load on the member was large, and an adverseeffect, i.e., significant deformation of the member was caused bycarrying out thermal curing of the comparative adhesive agent α with useof the curing oven.

As such, it was found that the comparative adhesive agent α which was aconventional one-part epoxy resin composition needed to be kept at ahigh temperature for curing, and this caused deformation of the memberdue to an excessive heat load.

Comparative Example 2

The comparative adhesive agent α and the comparative adhesive agent βwere applied to a PBT plate having a thickness of 100 μm as with Example2, and were then irradiated with laser light having a diameter of 10 mmand an output of 6 W for 10 seconds with use of the laser apparatus(manufactured by Jenoptik Japan Co. Ltd., JOLD-30-FC-12 808) whichemitted laser light having a wavelength of 808 nm.

A surface state of the comparative adhesive agent α was confirmed withuse of a spatula, and it was found that a liquid part remained and mostof the comparative adhesive agent δ was not cured. Moreover, a degree ofcure was evaluated, and a curing reaction rate was 15%. With regard to asurface state of the comparative adhesive agent β, many tucks were seenon the surface. A degree of cure was similarly evaluated, and a curingreaction rate was 54%.

By comparing these results and the result of Example 2 of the presentinvention, it was confirmed that the curing reaction rate in Example 2was significantly higher, and thus the present invention hadsuperiority. That is, the comparative adhesive agent α and thecomparative adhesive agent β which were normal one-part epoxy resinadhesive agents could not be cured by laser light, unlike the resincomposition in accordance with the present invention.

Example 6

FIG. 6 is a view illustrating results of observing a vertical crosssection of a cured product of an adhesive-agent-applied sample. (a) and(b) of FIG. 6 show results of observing, with a microscope (BX-60M,manufactured by Olympus Corporation), a vertical cross section (preparedby polishing) of a cured product of the applied adhesive agent Kobtained in Example 3. (a) of FIG. 6 shows a result of observing thevertical cross section with a magnification of 50 times, and (b) of FIG.6 shows a result of observing the vertical cross section with amagnification of 500 times.

(c) and (d) of FIG. 6 show results of observing a vertical cross sectionof a cured product of an applied adhesive agent A obtained in Example 1.(c) of FIG. 6 shows a result of observing the vertical cross sectionwith a magnification of 50 times, and (d) of FIG. 6 shows a result ofobserving the vertical cross section with a magnification of 500 times,as with (a) and (b) of FIG. 6.

In FIG. 6, reference numerals 10 and 10′ indicate cured products ofresin compositions. Specifically, the reference numeral 10 indicates acured product of the sample obtained by applying the adhesive agent K,and the reference numeral 10′ indicates a cured product of the sampleobtained by applying the adhesive agent A. The reference numerals 11 and14 indicate cured products of bisphenol A epoxy resins, the referencenumeral 12 indicates glass beads, and the reference numeral 13 indicatescarbon black.

As shown in (d) of FIG. 6, the cured product 10′ obtained by irradiatingthe resin composition in accordance with the present invention with aninfrared ray did not have a definite outermost surface layer. On theother hand, as shown in (b) of FIG. 6, the cured product 10 which hadbeen obtained by irradiating the resin composition in accordance withthe present invention with laser light had a definite outermost surfacelayer with a thickness, and the outermost surface layer was found tocontain, as a main component, a cured product 11 of the bisphenol Aepoxy resin.

INDUSTRIAL APPLICABILITY

The present invention can be suitably used in bonding and the like ofmembers in electronic components such as a relay and a switch. Fromthis, the present invention can be widely used in the overall electronicindustry.

REFERENCE SIGNS LIST

-   1: Resin composition-   2: Adherend-   3: Another adherend-   4: Terminal-   10: Cured product of resin composition

The invention claimed is:
 1. A resin composition comprising: a bisphenolA epoxy resin; an encapsulated curing agent including a core thatcontains a curing agent and a shell that covers the core; a filler; anda color material, the filler having a light-transmitting property andbeing one or more selected from the group consisting of fused silica,crystalline silica, and glass beads, the bisphenol A epoxy resin beingone or more selected from the group consisting of bisphenol A diglycidylether, hydrogenated bisphenol A diglycidyl ether, andtetrabromobisphenol A diglycidyl ether, the filler being contained in anamount that is not less than 10 parts by weight and not more than 70parts by weight relative to 100 parts by weight of the bisphenol A epoxyresin, the color material being carbon black, the color material beingcontained in an amount that is not less than 5 parts by weight and notmore than 7 parts by weight relative to 100 parts by weight of thebisphenol A epoxy resin.
 2. The resin composition as set forth in claim1, wherein: the core contains one or more curing agents selected fromthe group consisting of an amine compound, an imidazole compound, and athiol compound.
 3. The resin composition as set forth in claim 1,further comprising: one or more curing assistant agents selected fromthe group consisting of an amine compound, an imidazole compound, athiol compound, an acid anhydride compound, and a thermal acidgenerating agent.
 4. A cured product of a resin composition recited inclaim 1, said cured product comprising two or more layers, an outermostsurface layer among the two or more layers containing a cured product ofthe bisphenol A epoxy resin as a main component.